The strength composite pile has unique dual interface force transmission characteristics, and its bearing failure is prone to occur at external interface subjected to upper loads. The external interface load transfer system, composed of cemented soil and surrounding soil, is crucial for mobilizing a larger volume of surrounding soil to bear the superstructure load. However, its transmission characteristics are significantly affected by cement content, and the shear performance and evolution of external interface under cyclic loading are still unclear. In view of this, cyclic shear tests with constant normal stiffness were conducted to investigate the interface behavior under varying cement content, initial normal stress, and number of cycles. The results show that during cyclic shearing, the relationships between interface shear stress-shear displacement and normal displacement-shear displacement exhibit "spindle" and "∞" type hysteresis loops, respectively. The soil alternates between dilation and contraction, with a gradual reduction in normal displacement. As the number of cycles increases, both shear stress and normal stress decrease, while the residual normal stress ratio and residual shear strength show a decelerating decline. The interface friction angle initially increases and then decreases, and higher cement content reduces the variation in strength indices, indicating improved interface properties under cyclic shear. Additionally, the peak shear stress obtained from monotonic shearing after 100 cycles is greater than that obtained without prior cycling. It indicates that the attenuation of interface strength during cyclic shear is mainly due to reduced normal stress, which collectively influence the cyclic shear performance of external interface among strength composite pile with cemented soil strength.