A mathematic model of the pump power absorption and distribution in the LD side-pumped solid-state laser medium is set up. The pump power distribution in the single diode directly pumped laser rod with different pumped parameters is simulated using the method of ray trace. The effect of the different active medium′s absorption coefficient and distance between the diode and the laser rod on the pump power distribution in the laser rod is studied. The Gauss distribution of the pump power in the multiarray LD side-pumped laser rod is got under the condition of the laser rod with cooling system.