Abstract: SMAW has the characteristics of strong adaptability and easy operation，so it is widely used in deepwater subsea pipeline welding and laying. However, the traditional SMAW has the disadvantages of large metal filling amount and low efficiency, so this article describes a new small groove SMAW process experiment investigation in deepwater submarine pipeline welding, and compares its advantages, it carried on various mechanical capability test of the DNV SMLS 450 welded joint, all performance indexes meet the requirements of deepwater subsea pipeline design standards. The research results show that this technology can be popularized and applied in deepwater subsea pipeline welding construction.