Abstract: The Balangkou hydropower station locates on the tributary of the Dadu River and is a diversion station. The content of the sand and gravel filling materials with P5(particle size less than 5mm) is relatively high, which may influence the stability of dam. The rolling test is carried out in the construction site. This test determines the suitable filling thickness as 97cm. And the density, moisture content and settlement are measured as well during the rolling test. In addition, the grain content test, compaction test, penetration test and large triaxial test are carried out in laboratory. The grain content test shows that the sand and gravel are well graded and can meet the embankment dam design requirements. The optimum water content and maximum dry density are 5.32% and 2.42gcm-3 respectively. They are determined with compaction test. The average permeability coefficient is 2. 42210-2cms-1, which is obtained with penetration test. The strength parameters of the filling materials are =37. 711 and c=0,which is got with triaxial test. According to the test results, this study also checks the dam settlement, stress, seepage and stability comprehensively. The test results provide some guides for the long-term operation of the Balangkou Hydropower Station.