Building roof cornice waterproof structure

The utility model relates to the technical field of roof drainage, in particular to a building roof cornice waterproof structure which comprises a wall body, a roof and a waterproof assembly. The waterproof assembly comprises a water collecting tank, a water discharging pipe, a filtering plate, a filtering net, a sewage discharging tank, an ejector rod, a spring, a collision rod and a reciprocating pushing mechanism; during normal use, rainwater falling from a roof penetrates through the filter plate, falls into the water collecting tank and then is discharged from the water discharging pipe, due to the fact that the filter plate is obliquely arranged, part of impurities adhere to the filter plate after being intercepted, part of impurities fall into the sewage discharging tank under the action of gravity, part of rainwater flowing into the sewage discharging tank penetrates through the filter screen, and the rainwater is discharged from the water discharging pipe. When impurities adhering to the filter plate