In order to validate the accuracy of PIV（particle image velocimetry）

the paper carried out the experiment to measure the same propeller wake by using PIV and LDV（laser Doppler velocimeter） technique in the cavitation tunnel during the same period and working condition.The results indicate the PIV data get good agreement with the LDV data in the flow macrostructure.The PIV can display the velocity peak which is only span 8° in peripheral direction

but the velocity peak is smaller than LDV data.As a whole

the difference of PIV data and LDV data is about 2%～3%

further analyses show that the improvement of the positioning accuracy of PIV system can reduce the error.