Microstructure in the welding zone, mechanical and electro-chemical corrosion properties of high matching T91/T23 heterology heat-resisting steel welding joint were investigated. Experimental result shows that good welding joint was made by high matching and argon tungsten arc process. Micro-structure of the weld metal was tempering lath martensite with coarsing crystal grain. Microstructure in the HAZ of T23 steel side was mainly granular bainite and lath bainite; micro-structure of HAZ at T91 steel side was mainly tempered sorbite and tempered martensite. Hardness nearbynearby the fusion zone of T91 steel was the highese, and weak carbon migration were found nearby the fusion zone of T23 steel side weld junction. Corrosion resistance properties by turns of from large to small were: welded joint, T91 base metal , T23 base metal.