The invention relates to a BIM (Building Information Modelling)-based refuse landfill operation risk monitoring system and a BIM-based refuse landfill operation risk monitoring method. The BIM-based refuse landfill operation risk monitoring system comprises a landfill BIM, a landfill risk source identification monitoring module, a landfill overall progress information acquisition module, and a landfill operation cost information acquisition module and a visible 5D (5-Dimensioanl) risk pre-warning module. The BIM-based refuse landfill operation risk monitoring method comprises the following steps: (1) collecting high large side slope stability influence factors, measuring periodically, measuring a leachate leaking situation through a sensor which is pre-buried in an impermeable layer, and monitoring underground water and atmospheric environment around a landfill in real time; (2) storing information in classifications, encrypting and establishing a database, and mapping database response to the BIM; (3) showing and displaying 5D risk pre-warning monitoring system effect by the BIM in different periods.