Abstract: East Sichuan parallel ridge valley is a typical geological and geomorphic unit in Southwest China, with widely developed stepped slopes and frequent landslides, which have seriously threaten regional security. There were 999 hidden geological disaster points in Dazhou and Guang'an, including 781 landslides, accounting for 78.18%. At present, there is a lack of systematic research on the formation and evolution law, structural disaster control mechanism and landslide genesis of the special geomorphic unit of stepped slope. Based on the theory of geological structure, engineering geology and rock mechanics, the formation and evolution, structural characteristics and landslide disaster mechanism of stepped slope in the parallel ridge valley area of Eastern Sichuan were systematically explored using the methods of field geological survey, typical section measurement, lithology test and theoretical analysis. The results are as follows. ① The evolution of the stepped slope is the result of the coupling of tectonic movement, lithological differences, climate effects and external forces. And its evolution process mainly goes through four stages, that is tectonic formation, differential weathering, river erosion, landslide transformation/human activity intervention. ② By controlling the stress distribution and stability boundary of the slope, the consequent slope configuration and chair slope structure formed by fold structure have significant macro disaster control effect on landslide development. ③ The widely distributed lithological combination of soft and hard sand mudstone interbedding provides the material basis for the formation of stepped slope, and the characteristics of easy weathering and softening of its interface become the potential sliding surface for landslide breeding. ④ The infiltration softening effect of heavy rainfall and the disturbance and damage of human engineering activities, such as highway construction and building houses on cut slopes, are the two major external causes that would trigger the stepped slope landslide. The research results can provide theoretical support and scientific basis for the early identification, risk assessment and precise prevention of stepped slope landslide disaster in the parallel ridge valley area of Eastern Sichuan.