Based on the previous work, we propose here a designing method of optical resonator with an elliptical refractive index profile of dielectric. Moreover, some influences of thermal effects on the transversal field distribution, the orientation of polarization, as well as output power of b-axis Nd: YAP(Nd+Cr:YAP)CW laser are analysed. With these factors taken into account, we have been able to achieve 163W and 152W laser output with nearly linear polarization beam from 5.8 ×111mm Nd: YAP rod and 6.4×100 mm Nd+Cr:YAP rod with an over-all efficiency of 2.26% and 2.11% respectively. The depolarization of the laser beam is about 1:2900.