Abstract: The shear creep test of weak layers of water-saturated sandy mudstone was carried out on the slope 7-7 exploration line profile of the second mining area of Bailitan Open-pit Coal Mine. The results show that: when the normal stress is 0.05 MPa, 0.15 MPa, 0.25 MPa and 0.30 MPa, the long-term strength of each water-saturated sandy mudstone is 0.05 MPa, 0.09 MPa, 0.12 MPa and 0.14 MPa. When the normal stress is 0.20 MPa, 0.40 MPa, 0.60 MPa and 0.80 MPa, the long-term strength of each water-saturated sandy mudstone is 0.09 MPa, 0.12 MPa, 0.17 MPa and 0.22 MPa. Accordingly determine the weak water-saturated layer cohesive force is 40 kPa, and internal friction angle is 12 °; after the construction of the drainage project, the final slope angle can be slowed down from the originally designed 36° to 32°.