Nowadays, there is a great demand for rechargeable battery in the world, especially for the innocuousness and nonpollution ones. In process of manufacture, the automatic production line is used to ensure the productive tempo, the first-rate quality and consistency. And in the automatic production, the battery case, the electric terminal and the relief valve etc are welded by laser. So the battery laser auto welding technologies emerge as the times require. We make a summary of welding theories, research findings, techniques and the software and hardware design for the critical component in this article. We explain some questions that should be solved in the end, and give the developing direction for the future.