The utility model discloses an oil -water separating device, including the controller, the deoiling machine, the bilge pit, waste liquid collecting tank, leakage fluid dram, level gauge and fluid -discharge tube on the overflow launder lateral wall with the overflow launder that the degrease case that contains the mixed liquid of profit is connected, are located to the degreasing fluid collection box, fluid -discharge tube one end is connected with the leakage fluid dram, and the fluid -discharge tube other end is connected with waste liquid collecting tank, is equipped with the solenoid valve on the fluid -discharge tube, the utility model has the characteristics of the controllability is good with stability, and it is efficient to degrease.