Abstract: The pressurizer spray control valve is the key equipment used for pressure control of the reactor coolant system and maintaining uniform water chemistry in the primary circuit in nuclear power plant. In view of the fracture case of the disc spring of the pressurizer spray control valve in a nuclear power plant, through the methods of macro morphology analysis,size measurement, residual stress test, chemical composition analysis, hardness test, microstructure comparative analysis, and second phase analysis and fracture micro morphology analysis, it is concluded that the reason for the fracture of the disc spring is the improper heat treatment process and a large number of cracks at the grain boundary of Phase δ, resulting in the decrease of toughness and intergranular brittle cracking under external load. Then, the requirements for the solution heat treatment of the disc spring are clarified, that is, the solution heat treatment is carried out at the minimum temperature of 925～1010℃ and cooled by air cooling or faster method, and then the structural hardening treatment is carried out, including maintaining at 720±10 ℃ for 8 hours, then cooling in the furnace to 620±10 ℃ and maintaining at this temperature for 10 hours, and then air cooling.