As a new branch in non-thermal plasmas, plasma-liquid technology is characterized by low temperature, mass and heat transfer effectiveness, atmospheric-pressure operation and high reactivity. Process intensification techniques based on liquid plasmas have wide applications in nanofabrication, volatile organic compounds decomposition, sterilization and disinfection, chemical synthesis, etc. Taking the synthesis of nanomaterials by the liquid plasma as the research object, firstly, the reactive radicals that may exist in the system are introduced, together with the relevant characterization methods and possible reaction mechanisms; afterwards, the most widely adopted plasma-liquid systems are illustrated, which can be divided into non-immersed systems and immersed systems according to whether plasma is formed within the bulk of electrolytes; furthermore, several typical examples of nanomaterials synthesized by the plasma-liquid method are presented, with a summary of the state-of-art research in this field, finally, the challenges and development trends are discussed.