Abstract：Micro-pile composite structure has been widely applied to landslide treatment engineering due to its many advantages；and the engineering effect is very evident. But at present，few researches on the anti-sliding mechanism of the structure have been done. In order to provide theoretical support and technique service for the design and construction，the corresponding studies must be urgently conducted. Three types of the micro-pile composite anti-sliding structures have been summarized according to their setting places on the slope，namely，type of slope surface reinforcement，type of slope step reinforcement，type of slope foot reinforcement. Some key problems and applicable conditions are discussed for the design of these structures. Among these structures，the composite structure of micro-pile fixed by the tip beam is usually more adopted in projects. According to the relationship of pile-soil interaction，the anti-sliding mechanism of the composite structure is discussed. The composite structure improves the shear strength of the sliding surface；and the pile-soil system behaves better in anti-sliding effect. The anti-sliding mechanism of the system is not same as the one of the common retaining pile. The anti-sliding effect of the system is achieved by the tensile strength of the micro-pile and the bearing capacity of foundation of soil and pile，but not by the whole bend ability as the common retaining pile. In order to obtain the axial force of the micro-pile，the design theory is put forward according to the method of elastic foundation beam with restriction of transverse deformation. Application of the design theory to a slope project shows that the theory is reasonable and easy.
