The invention discloses a hydraulic oil precipitation tower of a hydraulic test bench. A precipitation container is mounted on a precipitation container holder. A copper wire mesh is arranged on the upper portion in the precipitation container. A liquid level control relay is arranged in the precipitation container. Valves are mounted on the side surface and the lower portion of the precipitationcontainer. According to the hydraulic oil precipitation tower of the hydraulic test bench, hydraulic oil which is used by the hydraulic test bench and does not meet the cleanliness standard is precipitated and reused through the hydraulic oil precipitation tower, waste of hydraulic oil is avoided, the cost is lowered, and the operation is simple.