Abstract: The microbial-induced calcite precipitation (MICP) is a new method for reinforcing geotechnical materials with environmentally friendly bacteria. The test results show that the stiffness, strength and dilatancy of the MICP-treated sands are enhanced, while the compressibility is reduced. In view of the mechanical properties and deformation characteristics of the MICP-treated sands, a state-dependent elastoplastic constitutive model for the MICP-treated sands with non-associated flow rule is established in the framework of critical state soil mechanics theory. In the new cementation degradation rule, the cementation degradation rate is related to the accumulation of plastic strain and the confining pressure. Then, the drained triaxial tests on the MICP-treated sands are simulated by the proposed model. The results show that the proposed model can well simulate the stress-strain relationship and dilatancy behavior.