Abstract: The undulatory biomimetic propulsor is a new underwater propulsor which emulates the swimming mode of Gymnarchus Niloticus.It can move forward,backward or brake depending on the undulatory motion of the flexible fin.To realize the undulatory control of the flexible fin,a locomotory model is analyzed and a distributed control structure is designed.In addition,a fuzzy coordinated control system with some self-adaptive capability is put forward.It combines the fuzzy controller and the self-adaptive unit,achieving the undulatory control of the flexible fin in uncertain environments.In the end,the control system is verified by pool experiments.