Pipeline socket weld is widely applied in the installation and joining for small caliber pipeline nuclear assistant system,it is a special form of fillet, but can not be manufactured according to the general fillet technical requirements,it had been sorted out of HAF603 lawful regulations and RCC-M specification due to special requirement. The socket welding structure is analyzed and the requirements of fillet size is determined,the welder qualification, principle of welding procedure qualification and the key points of product welding procedure are expound. The inspection requirements of welds are concluded to provide reference for the quality control and management of pipeline socket welding.