The invention discloses a large-span railroad bridge inspection system and method based on the BIM technology. The system comprises a planning module and a visual BIM model disease library construction module which operate at a server side, and an information consulting module and a disease input module which operate at a client side. The plan making module is used for making a bridge inspection plan. The disease library construction module of the visual BIM model is used for realizing correlation between the lightweight BIM model and the disease library and constructing the disease library ofthe visual BIM model. The information consulting module is used for downloading the inspection plan and the large-span railroad bridge lightweight BIM model from the server to consult the inspectionplan and bridge attribute information. The disease input module is used for checking corresponding parts of the bridge according to the inspection plan, selecting members with diseases through a BIM model, selecting specific types and degradation levels of the diseases according to actual disease conditions, and finally realizing accurate positioning and unified and standardized description of thediseases.