In order to solve the problems of high cost and short life span in current die manufacturing,a method tomanufacture forging die via steel casting surfacing is proposed.In view of the control of welding thickness,withthermal cycle curve method,the welding and tempering process is simulated on a simplified finite element model ofthe ZG310- 570 surfacing die by means of finite element analysis and experimental verification,and the temperaturefield and the residual stress field varying with welding thickness are analyzed.The results show that (1) finite ele-ment analysis is effective in simulating the manufacturing process of forging die; (2) the equivalent stress near thewelding joint decreases as the welding thickness increases until the latter reaches 15 mm; (3) the residual stressfar away from the welding joint increases with the welding thickness,and the impact of weld bead on the substratesubsequently strengthens,and thus the possibility of defect of steel casting material in use increases significantly.When we take into account such factors as the influence of welding thickness on cast- steel substrate and the manu-facturing cost,15 mm should be regarded as the optimal welding thickness of the surface layer of steel casting.