In order to solve the problem of thermal effect caused by LD end-pumped rod Nd:YAG crystal, a thermal model of Nd:YAG crystal was established, and the temperature field distribution, stress field distribution and thermal variation of incident end face were quantitatively calculated by using heat conduction theory and finite element analysis method. The influence of pumping spot radius and pumping power on crystal temperature field and stress field is also analyzed. The results show that: When the pump power is 10 W and the spot radius is 300 μm, the maximum temperature of the incident end face of the crystal is 316K, and the maximum stress per unit area of the crystal is 1.86×10⁷ Pa and 3.28×10⁷ Pa, respectively, when the side is unconstrained and when the side is constrained. The maximum shape variables of the incident crystal end face are 2.81×10^-4 mm and 3.01×10^-4 mm, respectively. The maximum temperature, the maximum stress per unit area and the thermoforming variable of the incident end face of the crystal increase with the increase of the pump power, and decrease with the increase of the spot radius. The results provide an important theoretical basis for optimizing the design of LD end-pumped Nd:YAG crystal laser and reducing the thermal effect of the crystal.