Collapse, as a common geological hazard in China, are widely distributed, highly concealed, sudden, and pose significant risks. In southwestern China, where disaster-prone red beds are extensively distributed, high cutting slopes are highly susceptible to landslides and collapses if not promptly managed, especially under the combined effects of back-end catchment and freeze-thaw cycles. Taking the collapse at Shejian Town in Guangyuan as a case study, on-site investigations, image analysis, and formula calculations were conducted to examine the failure mechanisms of red bed high cutting slopes influenced by back-end catchment and freeze-thaw effects, aiming to provide insights for disaster prevention in infrastructure development within red bed regions. The results indicate that the unique topography and climate conditions of the study area contribute to abundant rainfall, creating a waterintensive environment due to the extensive back-end catchment in the collapse area and infiltration from irrigated farmlands. The prolonged saturation of rock masses, combined with repeated freeze-thaw cycles, significantly weakens the rock strength, reducing the tensile strengths of sandstone and mudstone to 166.12 kPa and 72.77 kPa, respectively. Both values are lower than the fracture water pressure of 174.87 kPa in the fractures of the red bed cut slope, ultimately leading to the occurrence of the collapse. Given the variations in failure modes of red bed high cutting slopes with different rock structures under the effects of back-end catchment and freeze-thaw cycles, it is recommended to enhance drainage measures during prevention efforts and to implement targeted treatments based on the identified failure modes.