Abstract: ne-dimensional invariable temperature phase change interface model on CPL capillary wick evaporator is presented as follows: the temperature of evaporator wall, liquid and vapor only change along the axis direction, there is a vapor-liquid interface with saturation temperature between the wall of evaporator, vapor and liquid, at with heat transfer occurs. Based on this model, the one-dimensional energy conservation equation with a special term of inner heat source is applied to solve the temperature profile. In the calculation, several heat transfer coefficients are evaluated and recommended. Giving the boundary conditions, the temperature field of the evaporator can be obtained numerically. The wall temperature values from numerical calculation have acceptable agreement with that of experimental results.