Abstract: Anti-radiation barite material was added into concrete to simulate nuclear power concrete, and specimens with different crack depths were designed. The intercept and sound velocity of the corresponding specimens were obtained by fitting the acoustic parameters of non-crossing joints. The acoustic parameters of cracks at the corresponding measuring points were determined by the first wave inversion of ultrasonic method, and the measured crack depths were calculated. Based on the time interval method, the corresponding error range between the designed crack and the measured crack is obtained by calculating and analyzing the crack depth of 40-80 mm. The results indicate that the depth of crack is deeper, the error will be larger due to the complexity of working conditions. The first wave inversion method has high accuracy.