The dewar activation process will cause the temperature of the detector chip to overshoot and cause the chip to fail. The temperature distribution in the process of dewar activation is analyzed by simulation. The main heat transfer path of the detector chip with temperature rise and overshoot during dewar activation is studied.A scheme of getter baffle is proposed, which can reduce the maximum surface temperature of the detector chip from 105 ℃ to 85 ℃,and solve the problem of temperature overshoot in the activation process.