Abstract: In order to improve the detection accuracy of welding residual stress by ultrasonic method, the acoustoelastic coefficients of the base metal zone, heat affected zone and melting zone were calibrated.Based on the calibrated value of acoustic elasticity coefficient and zero stress benchmark, the residual stress test results of Q345qD welded steel plate were revised, and the blind hole method was used to verify the ultrasonic test results.The test results show that there are large differences in the acoustic elastic coefficients of the base material zone, heat-affected zone and melting zone; by correcting the acoustic elastic coefficient and zero-stress reference of the heat-affected zone, the overestimation of stress in the area can be reduced.The results of blind hole method and ultrasonic method have the same trend and close values, which verifies the accuracy of the results of welding residual stress detected by ultrasonic method.