Abstract: For first and third class boundary condition the temperature distribution of monocline laser crystal in a cross section perpendicular to rod axis during the lamp pumping process is calculated in this paper.It is shown that the temperature distribution exhibits radial parabola function and the isothermal line is circularity for first class boundary condition,whereas it is elliptic or hyperbolic function and the isothermal line is ellipse or hyperbola for third class boundary condition.The larger the difference between the principal thermal conductivity is and the lower the cooling efficiency of cooling agent is,the larger the difference with circularity is.Increasing cooling efficiency of cooling agent the difference with circularity will be decreasing.