Abstract: In order to reduce the test cost and shorten the test cycle of the marine current turbine,the correlation between the design and test of the marine current turbine and the wind turbine was studied. According to the similarity criterion,variable chord length rotor and equal-chord length rotor of 300 W marine current machine were designed by the design method of wind turbine blade. The rated velocity ratio of water flow to air is 1∶10 based on equal Reynolds number,and the rated speed of rotor is obtained from the same tip speed ratio. The output power of the two units was tested by vehicle-mounted test and flume test respectively. The wind speed is 8.31 m/s and the flow speed is 0.90 m/s when the equal chord length rotor type unit reaches the rated power,and the velocity ratio is close to1∶10. In the vehicle-mounted and flume tests,the Reynolds numbers of the two units are in the same order of magnitude,and the ratio of the tip speed ratio is slightly more than 1. The results show that both units meet the design requirements,so it is feasible to use this method to design marine current turbines.