The passive oil-water separator is that in the process of recycling tableware, chains, restaurants and unit canteens, the remaining tables and the waste from the bottom of the chafing dish are dumped into the equipment, the residue is left on the filter screen, the water is discharged into the sewer network from the sewage outlet, the oil is automatically discharged into the oil collecting tank from the separation chamber, and the oil is quickly classified from the source and collected in a reduced quantity. It saves manpower costs, improves the environment of the kitchen, and realizes the first step of “resource utilization”. (Sustainability)