Abstract: AP1000 reactor coolant pump uses the shielding pump with high inertia flywheel,and its cleaning,lubrication,sealing and cooling function are realized by auxiliary impeller to circulate the cooling water.No repair is required in the design life of 60 years.Canopy seals weld,as the RCP installation welds between the moving parts and the pump shell,acts as the seal of the internal circulating cooling water of the RCP.The Canopy seals qualification of welding procedure,type tests,and welding process control of site installation,nondestructive testing of quality control are discussed,in order to ensure the safety,quality and progress of AP1000 RCP installation welding on site.