The main road of the Zhicheng port area in Yibin Port is a long bedding slope with sandstone-mudstone interbedding，and the rock inclination is 16°. Its stability and treatment measures are particularly important for the construction of the port area. According to the deformation and failure characteristics of the slope found in construction，this paper analyzes the failure mechanism and stability of the slope through geological mapping，drilling，borehole television utilization，laboratory tests，and experience in similar engineering. The analysis results show that soft and hard rock interbedding，unfavorable bedding geological structure，gravity stress of the slope，poor properties of interlayer structural plane，slope toe excavation，and precipitation are the main reasons for the instability of the gently inclined long bedding slope with sandstone-mudstone interbedding. After the anti-slide retaining measures are taken，the stability of the slope is guaranteed.