This research focuses on the structure of a certain type of crane ship. It adopts post-weld heat treatment as a measure to eliminate welding residual stress and studies the residual stress status of the structure as well as the effectiveness of the elimination measures. Firstly， two groups of test plates in welding state and after post-weld heat treatment were used to detect and compare the welding residual stress. The results showed that the maximum longitudinal residual stress of the test plate in welding state reached 552.5 MPa， close to the yield strength of the material. The maximum longitudinal residual stress of the test plate after post-weld heat treatment was 385.3 MPa， reduced by 167.2 MPa compared with the welding state， a decrease of about 30%. At the same time， the distribution of residual stress was obtained. Furthermore， post-weld heat treatment was applied to the weld seams of the crane ship''s guide base structure， and stress detection was conducted. The maximum longitudinal welding residual stress was 310.8 MPa， far below the yield strength of the base material.The research indicates that the welding residual stress of the heavy-gauge steel plates in the crane ship is relatively high in the welding state， and measures need to be taken to eliminate the residual stress. Post-weld heat treatment can significantly reduce the level of welding residual stress in heavy-gauge steel plates， which is both economical and easy to operate. Therefore， post-weld heat treatment isrecommended for weld seams of heavy-gauge steel plates during the construction of crane ships to eliminate welding residual stress.