A method and system for site selection of a 110kV substation, the method comprising the steps of: separately obtaining the main transformer capacity, load rate, total capacity of the installed distribution transformers, interval utilization ratio, 10KV line overload rate, 10KV line non-transferable rate, 10KV line trunk overlength rate; respectively determine the correlation degree of each 110kV substation according to the main transformer capacity and the distribution transformer total capacity; Index standardization; combining the 10KV line overload rate, 10KV line non-transfer rate, 10KV line trunk overlength rate, and the load rate, correlation degree, and interval utilization rate after standardization of indicators, determine the coordination of the site selection plan corresponding to each 110kV substation degree; select the site corresponding to the site selection scheme with the highest degree of coordination as the final site, which can improve the coordination of medium-voltage distribution network operation while ensuring the reliability of the distribution network.