A full-size three-dimensional model of large-scale rectangular surface-wave plasma (SWP) source was built, the power deposition problems of SWP source based on collision mechanism were investigated through numerical simulations. The microwave reflectivity curves varying with plasma parameters were obtained, and the influence of different antenna arrays on power deposition is analyzed. The results show that the power deposition of uniformly discharged SWP source mainly depends on plasma property, and too big or too small plasma density is unfavorable to the energy absorption. In the range of working gas pressure, SWP source can achieve effective power deposition only through collision mechanism, and the absorption rate of microwave can reach more than 80%, which agrees with the existing experimental result. The results also show that compact and intensive surface wave is more favorable to the absorption of microwave.