The invention discloses a site drainage performance test method for a retaining engineering reversed filter. The site drainage performance test method comprises the following steps: 1, selecting a weep hole on a retaining engineering system reversed filter as a test weep hole, and carrying out temporary plugging on other common weep holes; 2, injecting a certain amount of water into the reversed filter from one side, near rock and earth mass, of the reversed filter through an intake system, obtaining displacement through a displacement measurement system with a certain period of test time, and obtaining the height of a water head at the position of the test weep hole through a monitoring system; 3, changing the injection displacement, repeating the step 2, and obtaining the measurement data of multiple displacements and the height of the water head at the position of the test weep hole; and 4, calculating the equivalent permeability coefficient K(m/s) of the reversed filter according to the measured displacement and the height of the water head. The test method disclosed by the invention is novel in idea, easy to operate the flow, strong in repeatability, and simple and convenient in test equipment, and has strong site operability.