The detection method of partial discharge（PD）ultrasonic array is a new method that applies the array sensors and array signal process technique to the PD detection. It has high signal-to-noise ratio and reliability of detection performance. Compared with the full array

the structure of sparse array detection system meeting the ac curacy of the direction is simpler and cheaper. The existing sparse structure optimization design algorithm is complex

and affects the success rate and accuracy of detection. Accordingly

a method of sparse structure optimal design for the CRPDUAS（the circular ring partial discharge ultrasonic array sensors） is presented. Firstly

the method of dimensionality reduction transforms the position of planar two-dimensional concentric ring array into one-dimensional linear array by using genetic algorithm to perform linear array search

and then restore to the concentric ring array when calculating its performance

so optimized sparse structure of circular arrays is obtained. At last

the simulated the sparse structure by music direction proves the correctness and effectiveness of the method.