Abstract: The numerical computation for an end-and-side pumped DPL indicates the temperature distribution in the cross section of the crystal is nearly axis symmetric, and the more proportion the end-pumping power occupies, the more axis symmetric the temperature distribution is. The thermal effect in an end-and-side pumped DPL was approximated with an equivalent lens. The calculation method for the focal length of the thermal lens was introduced. The influence of the thermal lens effect caused by combination pump on the spot radius of the fundamental-transverse-mode oscillation beam and the diffraction loss was analyzed. The proportion variation of the end-pumping power has some influence on the focal length of the thermal lens under a given total pumping power. The influences of the thermal lens effect on the oscillation beam radius and diffraction loss can be reduced by increasing the proportion of the end-pumping power.