Abstract: Thermocouple was adopted to obtain welding thermal cycle in 10CrNiCu steel by hybrid laser-MAG welding and traditional MAG welding processes. The microstructure and M-A constituents were also analyzed by optical microscopy. The experiment result shows that, compared to traditional MAG welding processes, the residence time upon 1 100℃ of HLAW was relatively smaller, the heating rate and cooling rate of thermal curve were greater, and the pattern of the welding thermal cycle was rapid ascending and descending; the HAZ consists of granular bainite, bainite, granular structure and M-A constituents; and the number of dispersively distributed fine M-A constituent decreased in HLAW。