Nuclear grade main equipment has been subjected to high temperature, high pressure and neutron irradiation for a long time in service, and its quality and safety requirements are very high. Welding, as a basic means in the manufacturing and installation process of main equipment, has a great impact on the quality and safety of the main equipment. This paper briefly discusses the types, methods, welding materials and existing problems of main nuclear power equipment in China. This paper analyzes the causes of several difficulties in welding, such as nickel base alloy welding, localization of nuclear grade welding materials and surfacing welding of cobalt base alloy, and puts forward solutions. The development direction of welding technology for nuclear grade main equipment is briefly summarized and prospected. It is proposed that numerical simulation, digital welding construction, additive manufacturing technology, application of advanced welding methods and intelligent welding should be the main development directions in the future.