Abstract: Taking the micro pile foundation of a tower in Western Sichuan mountain area as the research object, the load displacement curve, stress type and engineering performance of micro pile with different pile length and diameter under load were analyzed numerically with ABAQUS software. The results show that the displacement of pile top decreases with the increase of pile length and pile diameter. According to the stress type, when the pile length is short and the pile diameter is large, the micro pile is friction end bearing pile; When the pile length is long and the pile diameter is small, the micro pile is end bearing friction pile. With the increase of pile length and diameter, the bearing capacity of pile increases, the bearing capacity of concrete per unit volume decreases, the stability of pile increases and the economy decreases. In combination with the actual load bearing requirements and construction difficulty of the project, a 2×2 pile group composed of micro piles with a pile length of 8 m and a pile diameter of 300 mm is selected as the engineering test foundation.