Abstract: The irrigation method can directly detect the density of the filling body. It has the merits of simple principle and easy to use, so it is widely used in the quality inspection of the filling materials of earth rock fill dams in the water conservancy and hydropower projects. But in the actual engineering tests, many factors will affect the accuracy of the test results, and a lot of abnormal and unreasonable results are got. Therefore, it is necessary to analyze the influence factors by combining the practical quality testing experience of constructing earth rock fill dams. The relevant measures to eliminate or reduce the influence factors are put forward through experimental study.