The invention discloses a heat treatment process of a nuclear first-grade squib valve shearing cap. The process specifically comprises the steps of: a) material selection; b) charging pretreatment; c) empty furnace heating; d) charging; e) heating; f) aging treatment; g) cooling; and h) secondary aging treatment. The process is simple in flow, unique heat treatment process is adopted, the product quality is guaranteed, and treated products are enabled to achieve reliable high-temperature performance, creep resistance and corrosion resistance.