This paper presents an experimental study on the structural and motion parameters of a biomimetic mechanical fin, as actuators for biomimetic underwater vehicles, and their influences on its propulsion performance. Orthogonal experimental design method is employed to optimize the test scheme due to its capability of reducing experiment time and rapid determination of influencing factors. A L64 orthogonal array is adopted in our seven-factor mixed factorial experiment with three structure parameters and four motion parameters. The experimental results of range analysis and variance analysis are discussed. The statistic results show that the fin-ray configuration, sway frequency, wave number and rigidity of membrane are the primary factors affecting the integrated propelling performance of the biomimetic mechanical fin. Optimizing these parameters needs to compromise the propelling speed, efficiency and maximum output power of the actuator. The analytic results are also in agreement with theoretical analysis and simulation study on inclined-angle of fish fin-ray. Consequently, proper modification of the inclined angle of the fin-ray might improve not only the propelling speed and acceleration, but also the propelling efficiency.