In this study, the Discrete Element Method (DEM) was employed to investigate numerically the effects of hydrate cementation and intermediate principal stress on the stress-dilatancy relation of grain-cementing type methane hydrate-bearing sediment (MHBS) by conducting a series of conventional and true triaxial tests. A novel 3D thermo-hydro-mechanical-chemical (THMC) contact model for MHBS was employed. The numerical results show that with increasing hydrate saturation and back pressure, or decreasing confining pressure, temperature and salinity, the stress-dilation relation of grain-cementing type MHBS evolves from dilation-dominant to bond-dominant. For the clean sand samples, the relationship between the normalized stress ratio η / M cr and the dilatancy rate d is close under different intermediate principal stress coefficients. However, for the MHBS samples, this relationship is still affected by the intermediate principal stress coefficient b , due to the effect of hydrate cementation.