The prediction of the dynamic stress-strain relationship of compacted loess is essential in the projects of gully reclamation for farming and cutting mountains for city building in Loess Plateau. It is still difficult to predict the behaviors. To fill the gap, this paper formulates a bounding surface plasticity model for compacted loess subjected to cyclic loading. Specifically, a plastic modulus for cyclic loading is proposed to reflect the behaviors of accumulated strain, and an updated mapping rule is introduced. Furthermore, the influence of confining pressure and cyclic stress ratio on stress-strain relationship and modulus is shown by several case studies, which is verified by experimental tests of compacted loess. The results show that the plastic modulus reflects accumulated strain of compacted loess.The constitutive model considers the effect of cyclic stress ratio on dynamic stress-strain relationship and modulus of compacted loess because of the proposed plastic modulus and updated mapping rule. The results can give reference for analysis of long-term deformation of loess-filled foundation.