Abstract: TIG welding with filler wire was used in all position automatic welding of channel of stainless steel valve ball core in small space.An automatic welding platform was built by designing a TIG welding gun for small space operation and installing with wire feeder air protection cover red copper heat cooler and trolley walking device. Under the protection of multiple argon in small space of valve ball core, the weld of stainless steel valve ball core in V-shaped welding position was carried out. Cleaning up impurities and oil stains of the weld and its surrounding area before welding, using high purity argon for strict inert atmosphere protection during welding, it was to obtain weld with all performances that met technical requirements. After welding, microstructure and mechanical properties of the weld were tested and evaluated, the generation and cause of defects was analyzed, the process parameters were improved. Hardness of the weld, HAZ and the parent metal was tested and the corresponding process curve was drew to obtain the best combination of process parameters.