This paper adopts pulse TIG welding to weld the T250 maraging steel thin-walled spinning cylinder. By optimizing process parameters, weld joints with weld formation and internal defects meet the requirement of QJ175 -93 0 grade was obtained. Heat treatment was carried out to T250 maraging steel thin-walled spinning cylinder prior to weld and post weld. The influence of heat treatment on microstructure, microhardness,angular distortion and mechanical properties of weld joints was studied. The results showed that after aging treatment, reverted austenite exist in dendritic grain boundary in weld metal, microhardness is lower than basic metal. The grain near the fusion lion of welding heat affected zone grow and the largist grain size was 6 times of base metal. Heat treatment prior to weld decreased the angular distortion greatly. On the premise of 500℃ aging treatment post weld,aging treatment prior to weld improve the tensile strength and the bending angle. The best strength and toughness properties was obtained by 500℃ aging treatment prior to weld and 500℃ aging treatment post weld.