The invention relates to the technical field of lithium ion battery welding, in particular to a welding device for lithium ion battery processing. The welding device for the lithium ion battery processing comprises a machining table, a moving device, a positioning and fixing device, a welding device and a turnover device, wherein the machining table is arranged on the ground, a rectangular slidinghole is formed in the machining table, a lithium ion battery seat is arranged at the top of the machining table and located on the rectangular sliding hole, the moving device is arranged at the bottom of the machining table, the positioning and fixing device is arranged on the lithium ion battery seat, the welding device is arranged beside the positioning and fixing device and installed at the top of the machining table, the welding end of the welding device is aligned with the positioning and fixing device in a vertical and downward mode, and the turnover device is arranged beside the positioning and fixing device. According to the welding device for the lithium ion battery processing, by means of mutual operation among the moving device, the positioning and fixing device, the welding device and the turnover device, the tin soldering quality of a lithium ion battery is improved, manual assistance is not needed, manpower is saved, and therefore, the whole welding efficiency is improved.