According to the welding characteristics of nickel-based alloy 690,the welding current,welding voltage,welding speed,wire feeding speed and the form of tungsten pole are analyzed and controlled through a large number of experiments. The hot cracks and side wall unfusion defects of nickel-based alloy 690 pre-surfacing and safe end-ring welding are avoided. The test process parameters were validated and successfully applied to the welding of the pre-pile surfacing and the safety end ring of Sanmen 2#AP1000 evaporator.