To solve the severe thermal fatigue problem faced by air turbo rocket turbine guide vane under fuelrich gas environment, a quasi-static thermoelastic coupling model of a homogeneous plate was established according to actual working condition of turbine guide vane. The effect of gas properties on the temperature rise characteristics, stress and life changes of the plate subjected to thermal shock was obtained through Laplace transform and residue theorem. The results agree well with the three-dimensional thermal-flow coupling calculation results of turbine guide vane. The results show that the main components of fuel-rich gas is hydrogen, which has high specific heat at constant pressure and thermal conductivity. As a result, the convective heat transfer coefficient is more than twice that of lean-burn gas under the same conditions. And the heat flux, temperature rise rate, and equilibrium temperature of the plate are higher than those of leanburn gas plate under the same conditions. These cause the temperature gradient inside the plate to increase under fuel-rich gas environment. Due to the high temperature and large temperature gradient under fuel-rich gas environment, the peak thermal stress to increase by 80% and its life is shortened by 32% compared to the plate under lean-burn gas conditions. During the thermal shock, the stress increases rapidly to the peak and then decreases gradually. The main determinant of the peak thermal stress is the gas properties, and the post-peak is mainly affected by coolant temperature. Additionally, The influence of gas properties on peak thermal stress and life decreases with the increase of plate thickness.