Abstract: 10CrMo910 steel was welded by using proper parameters for solving the problem of cold crack and local hardening in the weld or adjacent metal weld of 10CrMo910 steel.Thermo-couples were laid in welded seam during welding to record temperatures in situ, and in-situ detection of thermal cycle about weld metal was realized.The detected maximum temperature during thermal process was 1701℃ and above 401℃ than the reported results about heat-affected zone.The welding thermal cycle curves with oil-cooled, air-cooled and sand-cooled for different cooling rates of welded joint were obtained.