The stress-strain characteristics of gas hydrate-bearing sediments (GHBS) are essential for achieving safe and secure extraction of marine natural gas hydrate. To quantitatively investigate the influence of hydrate formation on the mechanical properties of GHBS, laboratory tests were conducted under different confining pressures and various hydrate saturations, and it was found that hydrate primarily enhanced the cohesive strength of GHBS, while the internal friction angle remained relatively unchanged. To comprehensively describe the intricate mechanical properties of GHBS, the previously established elastic-plastic constitutive model was employed for predictive purposes. A comparative analysis revealed that the constitutive model exhibited a certain level of applicability. Subsequently, a computer program was developed for the constitutive model by leveraging the UMAT user material subroutine interface provided by ABAQUS. The program was written in FORTRAN language and integrated into ABAQUS, facilitating the implementation of the constitutive model. To validate the effectiveness and stability of the developed model, finite element simulations were conducted on single elements as well as triaxial specimens of GHBS. The results of these simulations confirm the efficacy and reliability of the developed model.