A small modular underwater propeller was designed in order to solve the problem of low efficiency and weak pressure resistance of small underwater vehicle propeller.The designed propeller adopts the sealing mode of oil bag and uses internal and external pressure difference to realize the self compensation,so as to avoid the failure of the whole propeller caused by slight oil leakage and ensure the reliability of the propeller.The sealing performance of self compensation module was analyzed by finite element method,the hydrodynamic performance of the propeller was calculated and simulated,and the pressure and thrust test was carried out.The test and simulation results show that the self compensating underwater propeller has good sealing performance and hydrodynamic characteristics,which verifies the reliability of the design.