The utility model discloses a road initial rainwater damming system mainly is difficult to the problem that realization branch matter is dammed to the road rainwater under the prior art, has provided the road initial rainwater damming system of the road initial stage rainwater that effectively dams, including rainwater collection system, municipal rainwater system and initial stage rainwater storage system, rainwater collection system is including setting up a plurality of inlets for stom water on the road, and hole rainwater grate suitable for reading is being collected including the collection hole that sets up below the road surface with setting up to the inlet for stom water, initial stage rainwater storage system includes that a plurality of initial stage rainwater are stored up the well and are used for communicateing each initial stage rainwater and stores up damming of well and manage, collect the hole and store up the well intercommunication through the connecting pipe that dams with the initial stage rainwater, collect the hole through municipal rainwater connecting pipe and municipal rainwater system intercommunication, the connecting pipe oral siphon open height that dams is less than municipal rainwater connecting pipe oral siphon open height. The utility model discloses the road initial stage rainwater that can effectively dam realizes that the branch matter of road rainwater is dammed.