Mid-infrared Er:ZBLAN fiber laser emitting at the wavelength of 3 μm is widely used in industry, medicine, military and other fields due to its advantages such as good beam quality, small size, coiling-ability and easy realization. In this paper, the development status of Er:ZBLAN fiber laser is introduced. The technical difficulties encountered in the development of Er:ZBLAN fiber laser are discussed. Moreover, their future development directions are also summarized and prospected. According to the current research situation, it is proposed that multi-stage amplification will be a method to further improve the single laser power of 3 μm Er:ZBLAN fiber laser. In order to breakthrough the power limit of single laser, the integration of single laser and fiber beam combination technology will become a research direction in the future.