Slope collapse is the primary problem of geological projects in slopes with interbeddings of soft and hard rocks in red bedrock area. This paper examines a highway slope in southwest area of China. The collapse mechanism of formation and the characteristics of structure are studied using field investigation. The slope characteristics of failure and deformation after collapse are studied with the nonlinear finite element method of two dimensions. The slope stability is also evaluated with quantitative method. The result shows that owing to the discrepant weathering, the lower soft rock mass has some notch that can cause the collapse and the cracks in the upper hard rock mass. The cracks link up gradually. If it is not stabilized in time, the upper hard rock mass can collapse when the cracks in the hard rock mass link up to 60% in thickness. Based on the comprehensive analysis of the present slope stability and the potential pattern of failure and deformation, the scheme is settled. It includes cleaning slope surface, cutting parts of the slope, hanging the net of reinforcing bar and sprayed concrete, reinforced concrete support column, and drainage system. The focal treatment measure is to control the development of the cracks in the upper rock mass above the notchand to make waterproof and drain establishment.