This paper studies the undulation control on the bionic device of long flexible fin based on undulation movement generated by the long flexible fin of Gymnarchus niloticus. Firstly, the principle of forming propulsion wave and the realization scheme of long flexible fin were studied. Secondly, a kinematics model was established to describe the undulation surfaces of the bionic device, the undulation control parameters which can be used in realizing multiple undulation modes of bionic object were distilled, and the methods of realizing some given undulation modes of long flexible fin were studied by simulations. According to the physical constraints of the bionic device, the criteria to judge the validity of these parameters were also presented. Finally, the paper studies undulation control strategy and control-flow of the bionic device of long flexible fin.The research result indicates that the bionic device of long flexible fin can imitate multiple undulation modes of bionic object via setting control parameters properly, and can realize multi-parameter control of propulsion wave. So, it can satisfy the unsteady hydrodynamic measurement demands of the bionic device with multiple undulation parameters.