Abstract: In order to solve the problem that waste heat accumulation occurs inside the crystal when the laser diode (LD) end-pumped microchip laser operates. Based on the working characteristics of mosaic Yb:YAG microplate laser crystal, a thermal model of Yb:YAG microplate with cooling side and bottom and heat exchange between pump end and air is established. According to the heat conduction equation, the temperature field, stress field and thermal deformation field of Yb:YAG microplate are calculated by finite element analysis, and the effects of pump power, pump radius and Gaussian order on the temperature field and thermal deformation field are quantitatively analyzed. The results show that if the laser diode with pump power of 50 W and pump Gaussian radius of 300 μm YAG microplate end-pumped, the maximum temperature rise of the crystal internal field is 67.75 K, the maximum thermal deformation in z-axis direction is 1.8351×10⁻⁴ mm, the maximum deformation in pump end-face is 1.8355×10⁻⁴ mm, and the maximum stress is 1.249×10⁸ N·m⁻². The results provide theoretical basis for the design of laser diode end-pumped Yb:YAG microplate lasers.