According to the laser three-level rate equation theory and spatial distribution of pump diode focusing,theoretical model of three-dimensional DPAL rate equations is established.The model was solved by numerical method with the boundary conditions of the laser system.The output characteristics of end pumped rubidium vapor laser were analyzed in detail.Meanwhile,the influence of some parameters on efficiency of mode matching,threshold pump power and the slope efficiency were analyzed,including focusing spot radius of pumping light,focusing position and gain cell length,etc.The influence of the medium length on the laser output and the threshold value was calculated at the best mode matching.In order to obtain the maximum laser output power,the optimization parameters of the laser system were given,including the medium length,the focusing position of the pump and the output coupling reflectivity.