Abstract: Nondestructive testing of valve steel castings is an indispensable part to ensure valve quality. Based on the test and analysis of sound field characteristics of WCB material, the paper described in detail test pieces making of WCB valve steel castings with irregular structure, the selection of special test software, test process design and test result analysis. The results show that the phased array ultrasonic inspection technology is easy to operate and fast, which can effectively detect irregular structure of valve steel castings in normalizing state, and solve the limitation of conventional nondestructive testing technology.