Abstract: In order to study influence of different guide blade number on internal flow and unsteady characteristics of submersible pump, taking a typical QJ submersible pump as research object, three different schemes with guide blade number of 6, 7 and 8 were established under condition of keeping basic parameters of guide blade unchanged． Based on turbulence model of RNG k-ε, submersible pump was calculated for both constant and non-constant under different guide blade number． Results showed that change in guide blade number has little effect on external characteristic curve of submersible pump． Increase of guide blade number has little effect on pressure pulsation at inlet and outlet of impeller, but has a significant effect on pressure pulsation between impeller and cavity of guide blade． Its amplitude increased with increase of guide blade, and pressure pulsation amplitude wass the largest at 8 blades．