The servo valve of aero engine vectoring nozzle is analyzed by the lumped parameter method. The variation of the time dependent temperature of the servo valve under the influence of ambient temperature, the initial temperature and the Joule heat of the servo valve is studied through the establishment of the corresponding mathematical model. The results show that: the steady temperature of servo valve only increases with the increase of ambient temperature and Joule heat, and is independent of the initial temperature of servo valve. The over temperature time of servo valve is shortened with the increase of initial temperature, ambient temperature and Joule heat. When the ambient temperature is 300 ℃ and the servo valve has a Joule heat of 0.08 W, the initial temperature changes from 50 ℃ to 100 ℃, and the over temperature time is shortened by 20.6%. When the Joule heat of servo valve is 0.08 W, the initial temperature is 70 ℃ and the ambient temperature rises from 250 ℃ to 400 ℃, the over temperature time is shortened by 60.8%. When the ambient temperature is 300 ℃ and the initial temperature is 122.6 ℃, Joule heat of 10 W compared with that of 0.08 W, the over temperature time is shortened by 38.3%.