Based on quantities of test data, a elliptic equation is set up for the elastoplastic stage of pressure meter test with the method of curve fitting; and then, the SMP yield criterion and ROWE flow rule are used to deduce the relationship matrix of the stress increment and strain increment in plastic stage. In the elastic stage, the stress and strain is supposed to obey the generalized Hooke’s law; so the elastoplastic constitutive model is set up, in which the stress-strain relationship is clear; and the parameters are easy to be obtained obtain from the pressure meter test. Accordingly, the calculating program is worked out to compare the model result and the actual test curve, which can validate the model primarily. Furthermore, the model is compiled as a UMAT subroutine, which can be used for finite element analysis in ABAQUS. The comparative analysis shows that, the deformation of this model is larger than that of elastic model and smaller than that of Mohr-Coulomb model, which is consistent with the model assumptions. The elastoplastic constitutive model of soil based on pressure meter test is easy to obtain the parameters and convenient to be used in engineering.