In this paper, three types of eight kinds of diode side-pumped structures were designed, and the corresponding theoretical model of pumping optics was constructed. The absorption efficiency and standard deviation of matrix elements under different structures were calculated by finite element analysis method. First, given the total pump power, chip spacing, doping concentration, etc., with the increase of the pump distance from 0~5mm, the absorption efficiency of laser crystal in the eight pump structures tended to decrease, and the standard deviation of matrix elements also decreased gradually. The standard deviation of matrix elements varied greatly when some structures were pumped at a close distance (0~0.3mm). In practical applications, the pump distance should be avoided in the above range. Secondly, under the same structural parameters, the absorption efficiency of the laser crystal was improved with the increase of the crystal doping concentration from 0.6% to 1.0%. At the same time, the increase of the doping concentration was the source of the reduced central peak of the cross section or light field depression in the radius direction. Therefore, the matching of doping concentration and pump distance will be an effective means to improve the uniformity distribution in the radius direction.