Abstract: 20 mm thick 2205 duplex stainless steel plate was welded by using high nitrogen electrode arc welding, and the microstructure and properties of the joint were analyzed. The results show that the strength and low temperature impact toughness of the joint meet the standard requirements. The strength of the weld is higher than that of the base metal. The impact toughness of the base metal is best, followed by that of the heat affected zone, and that of the weld is worst. The weld structure is mainly composed of ferrite phase and austenite phase. Austenite is distributed on the ferrite matrix in various forms such as block, strip and so on. In the weld near the fusion line, the austenite is mainly distributed in short rod and strip shape;coarse austenite grains appear at the bottom of the weld; secondary austenite precipitates in the center of ferrite matrix of heat affected zone at the weld bottom position. Compared with that of the welded state, the proportion of austenite in the weld after solution treatment increases, and with the increase of solution temperature, the proportion of austenite in the weld increases.The hardness of the joint shows a decreasing gradient from the center of the weld to the base material.