EPS composite soil is a new kind of lightweight fill material. Its engineering properties have been widely studied. However, the creep behavior has not been well investigated. In this study, triaxial undrained creep test is conducted on EPS composite soil regarding various confining pressures. Based on the testing results, a modified Singh-Mitchell creep model is established for EPS composite soil considering the influence of the deviator stress on the parameter m. Compared with the original Singh-Mitchell model, the modified creep model can well describe the creep behavior of EPS composite soil. It can provide references for engineers to design the project using EPS composite soil.