To optimize the calculation methods and application schemes for reinforcing landslides using grouted steel pipe micropile composite structures, the composition of single-pile composite structures and the combination forms of pile group structures were described. By taking the Bishop method as an example, a stability analysis method and the anti-sliding principle of side (sliding) slopes reinforced with grouted steel pipe micropile composite structures were proposed, and a calculation formula for the allowable shear resistance of the composite pile was derived. By taking a landslide case from a section of Lijiang?Panzhihua Expressway as an example, landslide stability analysis and landslide thrust calculation were carried out. The grouted steel pipe micropile composite structure was used to strengthen and treat the landslide in sections, and corresponding design schemes for landslide emergency rescue and permanent treatment were proposed. The original landslide section has operated safely for over three years after treatment, effectively verifying the good treatment effect of this composite structure. Meanwhile, suggestions were given on the calculation principles, design methods, and application schemes for landslide treatment using grouted steel pipe micropile composite structures.