The five laser-diode (LD) arrays symmetrically side-pumped Nd:YAG thin disk laser is investigated experimentally and simulatively. The coupling system is composed of astigmatic lenses and hollow wave-guide, and a 15 mm×1.5 mm Nd:YAG disk was used during the primary experiment. The average output power of the disk laser was 65.7 W in experiment with 10.5% optical-to-optical efficiency, and there is good fluorescence distribution in medium. The pump distribution of thin disk is obtained and analyzed by the ray tracing method. The divergence characteristics of the fast axis and the slow axis of LD and the scattering characteristic of thin disk side are homogeneously considered during the simulation. The simulation shows that the coupling efficiency of the coupling system is 88.3%, and the pump distribution in thin disk is ideal, which is accordant to the experimental result.