The invention relates to a machining process for an arc spring. The machining process for the arc spring is characterized by comprising the following working procedures of spring coiling, first-time stress relieving, spring grinding, bending for the arc spring, second-time stress relieving, shot blasting, hot stressing, sorting, angle rigidity and torque testing, fatigue life testing and surface rust-proof treatment. The forming process of the arc spring is provided, and by means of the forming process, the arc spring with the free angle larger than 45 degrees can be effectively formed, it isguaranteed that the hot relaxation rate of the spring is smaller than 2 %, the instantaneous torque is large, and the fatigue life is one million times or above; and the technical problems that in theprior art, the yield of the large-angle arc spring is low, and the large-angle arc spring cannot be normally used are solved.