Spatial distributions of pump beam and oscillating beam will be affected by thermal effect in solid state laser. The research shows that a specific pump power region is existed in end-pumped solid state laser. In this interval, pump beam and fundamental mode oscillating beam achieve large overlap in the gain medium under thermal effect, which results in higher efficiency of pump source and better beam quality of laser. Based on the characteristic, a laser is designed. Spatial distributions between pump beam and fundamental mode oscillating beam of the laser can achieve large overlap, and the beam quality factor is lower than 2.3 with pumping power ranging from 105 W to 115 W. Out of this range, the beam quality rapidly increases to more than 3. A new optimization algorithm is proposed to calculate the pump power region, which can find ideal pump power region rapidly in end-pumped solid state laser. Compared with the experiment, the pump power region of the proposed method achieves a higher level of compliance with experimental region, and the relative error is less than 5% with high reliability.