All-solid-state batteries are expected to achieve higher energy density and provide a higher safety rather than liquid batteries. As one of the core components of the all-solid-state battery, the thickness, ion transport capacity, mechanical properties, chemical/electrochemical stability and other properties of the solid electrolyte film play a crucial role in the performance of the all-solid-state battery. This review summarizes the processing methods of the existing solid electrolyte membrane. According to the solvent usage of the electrolyte membrane processing technology, it can be divided into three types of processing technologies, i.e., wet preparation, dry preparation and dry/wet preparation. The key technical indicators of the prepared solid electrolyte membrane, such as thickness, ionic conductivity, mechanical properties, battery properties and large-scale processing potential, are introduced. In addition, some challenges faced by different preparation processes and the future development direction are also summarized and prospected.Summary and ProspectsThe development of all-solid-state batteries puts forward new requirements and challenges for the processing and manufacturing of solid electrolytes. In this review, the processing technology of solid electrolyte in a relatively comprehensive and systematic way (i.e., dry preparation, wet preparation and dry/wet preparation) is introduced. Dry preparation mainly uses ball milling, roll pressing and other technologies, the processing process does not need to introduce solvents, avoid complex and cumbersome processing, efficient and environmentally friendly, and the prepared film thickness is easier to control. Wet preparation mainly uses magnetic stirring, ultrasonic and other methods to make the slurry mixed evenly, and then volatilizes the solvent through solution pouring, casting, freeze drying and other methods to form a film. The advantages of wet preparation are mainly that the prepared solid electrolyte film is more uniform and controllable. Dry/wet preparation mainly includes non-in-situ processing technologies such as 3D printing and electrospinning, as well as in-situ polymerization technologies such as photocuring and thermal curing. Among them, 3D printing technology has a high shapeability, which is easy to design the solid state battery structure. Electrospinning is convenient in the preparation of solid electrolyte film matrix. In-situ curing can achieve good interface properties and better integrate battery processing technology. Despite the existing solid electrolyte processing technologies, further research and attempts are still needed to achieve the large-scale production and landing of solid electrolyte membranes. The following aspects are concerned:1) To achieve both film thickness and mechanical properties. Making the film thickness thin to achieve a high energy density is one of the important goals of all-solid-state batteries. However, the reduction in film thickness can make it easier for dendrites to Pierce, leading to short circuits. Therefore, the mechanical properties of the films should be improved via introducing high mechanical strength polymers, adding inorganic fillers and roller compaction.2) To reduce production costs and improve preparation efficiency. Polymer synthesis usually involves relatively complex chemical reaction processes. In addition, the battery materials have generally high requirements for anhydrous and anaerobic environments. From raw materials to the production, the process steps need to be continuously optimized to reduce production costs and improve production efficiency.3) To promote the process of film preparation from the laboratory to industrialization. A basic research in laboratory is relatively easy to achieve due to its small scale. The assembled button battery has a small area, so its consistency is relatively better controlled. However, it will inevitably encounter a variety of problems after enlarging it. Some problems in wet method such as slurry defoaming and viscosity control need to be solved. The uniformity problem in dry method as well as the adaptation of new materials to the existing processing equipment all need to be continuously verified.4) Theoretical calculation and process production are closely integrated and mutually feedback, providing a more accurate and efficient path for the development of solid electrolytes.In general, there is still a long way to go to obtain a solid electrolyte film with ultra-thin, excellent electrochemical performance, stable interface, low cost and easy mass production. The progress of the process is also inseparable from the development of novel materials and the update of production equipment. It is thus necessary to integrate material research and development, process design, production and processing interactive interconnection, and truly achieve the combination of production and learning to grasp the initiative of all-solid-state batteries as soon as possible.