The 1Cr18Ni9Ti stainless steel sheet samples with the thickness of 0.7 mm were welded by laser welding and TIG welding, respectively, and the microstructure and mechanical properties of the weld joints were investigated. It was found that the width of the heat affected zone of laser welding sample was approximately 60 μm, and the microstructure in the weld was dominated by the columnar grains growing epitaxially to the weld bond. The width of the heat affected zone of TIG welding sample was about 1.3mm, and the twin was formed in the heat affected zone. The microstructure in the TIG weld was composed by the epitaxial columnar dendritic grains near the weld bond and the equiaxed dendritic grains in the middle of the weld. The formation mechanism of the microstructure in the laser weld and TIG weld was disclosed based on the columnar to equiaxed transition (CET) model. The microhardness and room temperature tensile testing indicated that the weld hardness obtained by laser welding and TIG welding were all lower than that of the base metal. The hardness distribution curve of the TIG welding sample was like a saddle with the hardness of the heat affected zone lowest. The strength of the laser welding sample is much higher than that of TIG welding sample.