The invention discloses a numerical simulation-based data-free regional rainfall station network site selection method, which comprises the following steps of S1, constructing a WRF mode, and constructing a specific application case of the WRF mode in a multilayer nesting mode for a region where a rainfall station network is planned to be arranged; S2, driving the WRF mode of the research area constructed in the step S1 by utilizing the obtained data, realizing operation and calculation of the WRF mode in a corresponding time period, and storing an operation result file in a folder; S3, utilizing a WRF mode post-processing tool to develop a corresponding program to realize precipitation data extraction, and storing the extracted precipitation data into a text file; and S4, calculating a corresponding numerical value index, and analyzing the numerical value index to determine the rainfall station network site selection. The rainfall distribution condition of the rainfall station networkarea to be laid is obtained by utilizing a numerical simulation means, the difficulty of laying the rainfall station network due to no rainfall observation data is overcome, and the rationality of laying the rainfall station network in a data-free area is improved.