Disclosed is a reno-mattress-structured anti-flushing water tank test apparatus and test method. The test apparatus includes a test water tank, a test slope protection is arranged at one side of the inside of the test water tank and is made from model sand meeting sediment incipient motion similarity and repose angle similarity, and a test reno mattress which meets size similarity and bearing similarity is laid on the slope surface of the test slop protection. At this moment, the left part of the water tank forms a test water channel, and water gates are arranged at front and rear ends of thewater tank. Through adjustment of the opening degree of the front and rear water gates, the depth and flow rate in the test water channel are controlled. In the test process, a simple variable including the flow rate, the depth and diameter of gravel in the reno mattress is controlled, and the anti-flushing critical damage flow rate of the reno mattress with different diameters of gravel filled indifferent water depth is obtained.