The transient processes of temperature rise and fall exist in laser crystal pumped by quasi-CW laser diode（LD）.Based on the heat conducting equation,a general analytical transient temperature filed expression of Nd∶YAG microchip end-pumped by the quasi-CW supper-Gaussian beam was obtained by the methods of the eigen-function and the constant variation.Meanwhile,the influence of the quasi-CW pump beam with different waist radius and pulse widths on the transient temperature filed of Nd∶YAG microchip were quantitatively analyzed.The results show that when quasi-CW LD end-pumps the Nd∶YAG microchip,the temperature distribution of Nd∶YAG microchip will undulate with pump pulse.And after a period of time,the temperature field will present stable periodic distribution.The transient temperature field of microchip will undulate around the temperature field end-pumped by CW LD.The fluctuant amplitude of temperature field is 12.1 ℃.And the temperature rise of microchip increases with the pump width or duty cycle of the quasi-CW LD.The research methods and results can also be used to analyze other transient thermal problems in laser systems.