A clear understanding of temperature variation of the sheet metal in immersion quenching process is indispensable for microstructural evolution of the metal material. It means specimen temperature variation in immersion quenching process remains to be further investigated. This work focuses on temperature variation of the 7075 aluminum alloy sheet in the immersion quenching process with the consideration of thermal radiation, boiling process and thermal convection. The proposed mathematical model was validated by the experiment data under different specimen positions and quenchant temperatures. Furthermore, the effects of the instability coefficient α in film boiling stage and the wetting parameter wp in transition boiling stage on temperature variation in boiling process were theoretically investigated. Both the experiment results and the theoretical prediction indicated that the temperature variation curves of different measuring points in boiling process are parallel during the quick immersion quenching process, and the temperature change rate in quenching procedure only depends on the quenchant temperature and the boiling stage.