The invention discloses a process method for controlling thermal deformation of plungers in a heat treatment process. The process method comprises the process steps of tool material preparation, toolcomponent processing, tool assembling, tool rotation testing, plunger heating and plunger straightness detection; and a rotating shaft enables the plunger clamping quantity to be reduced to 1/2 of thefull clamping quantity, the plunger clamping manner is kept to be the same as that of the full clamping quantity, in other words, 1/2 of a rotary disc is provided with the plungers, and the other 1/2area is not provided with the plungers. The heating time is set to have three stages, wherein in the first stage, the plungers stay in a high temperature zone for a long time, and the effect of rising the temperature of a base is achieved; in the second phase, the main purpose is to make the plungers to have long time to enable the temperature to diffuse into bodies after the plungers pass through the high temperature zone and the surface temperature quickly rises, the plungers uniformly deform, the original straightness is maintained, and the second stage accounts for 1/2 of the total heating time; and in the third stage, the rotation speed is relatively high, the rotation speed suitable for the device is 6 rmp, the time is controlled within 30 min, the plunger deformation quantity obtained after heating is small, and the straightness does not change significantly.