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The change of blade trailing edge shape will affect the wake structure of impeller outflow, which has a significant impact on rotorstator interaction (RSI) in the pump. To study the influence of long and short blades trailing edge shape on performance and rotorstator interaction in centrifugal pump by CFD, long and short blades trailing edge filing was applied on pressure and suction sides with different thicknesses respectively. The numerical simulation was carried out by using the SST-SAS turbulence model, and the accuracy of the simulation was verified by performance and PIV test. Rotorstator interaction in pump was analyzed by pressure fluctuation and vorticity distribution. The results showed that pressure side filing (PSF) can effectively improve the efficiency of centrifugal pump at nominal flow rate, and the greater the filing thickness was, the more remarkable the effect was. On the other hand, PSF can also obviously improve RSI in centrifugal pump at nominal flow rate, so as to reduce the energy loss of pressure fluctuation, improve the performance of centrifugal pump and prolong the service life of blades, while the suction side filing (SSF) greatly aggravated the rotorstator interaction. The distribution of pressure fluctuation and vorticity in frequency domain showed that the main frequency components of RSI in impeller passage were axial frequency and its multiplication, and the main frequency and secondary frequency of RSI in volute passage were fB and 0.5fB respectively. Compared with the main frequency vorticity near the trailing edge of the long and short blades, the effect of the trailing edge filing of short blade was more significant than that of the long blade. Evolution process of the vortices in RSI region demonstrated that the vortices in RSI region during short blade passed through the tongue were more intense compared with long blade, which determined the difference of RSI near the trailing edge of the long and short blades and resulted in a secondary frequency of 0.5fB.