The utility model provides a rapid detection device for the oil leakage of a hydraulic system. The rapid detection device for the oil leakage of the hydraulic system comprises a magnetic flap liquid level meter used for detecting the liquid level of an oil tank of the hydraulic system. A first magnetic maintaining switch and a second magnetic maintaining switch are mounted on the magnetic flap liquid level meter. The first magnetic maintaining switch is located above the second magnetic maintaining switch. The two magnetic maintaining switches are each connected with a relay in series and then are connected in parallel. The normally-closed contacts of the two relays are each connected with an alarm apparatus in series and then connected in parallel. Under the normal working state of the hydraulic system, the first magnetic maintaining switch is located at the position which is 8 cm to 9 cm lower than the normal fluctuation range of oil liquid in the oil tank of the hydraulic system. The normally-closed contacts of the two relays are connected with the alarm apparatuses in series and then connected with the same manual switch in series. According to the rapid detection device for the oil leakage of the hydraulic system, the defect that it is inconvenient to detect oil leakage at relatively covert pipeline parts of an existing hydraulic system is overcome, the oil leakage of the hydraulic system can be detected rapidly, and the rapid detection device is simple in structure, reliable to use and practical.