Abstract: The mechanical behavior of methane hydrate bearing soil is closely related to the characteristics of hydrate phase equilibrium. Compared with sand, clay has smaller pore size and the pore size has a great influence on the characteristics of hydrate phase equilibrium. A three-dimensional thermal-hydro-mechanical-chemical bond contact model for grain-cementing type methane hydrate-bearing clay is established by introducing the influences of the pore size on the phase equilibrium line. The numerical simulation of triaxial compression tests on the methane hydrate-bearing clay under different salinities is carried out. The macro- and micro-mechanical behaviors such as stress-strain curve, volume strain, number of bond breakage, aggregate crushing rate and strength characteristics are analyzed and compared with the mechanical properties of remolded clay. The enhancement of bond on the mechanical properties of the methane hydrate-bearing clay is discussed. The results show that (1) Under low confining pressure, with the increase of the salinity, the peak shear strength of the methane hydrate-bearing clay gradually decreases, and the strain softening is less significant. At the same time, the volume strain shows shear contraction first, then weak dilatation and then shear contraction. Under high confining pressure, it shows strain hardening and shear contraction. (2) With the increase of the confining pressure and salinity, the number of bond breakage and the aggregate crushing rate of the methane hydrate-bearing clay gradually increase. (3) Finally, through the analysis of the strength characteristics of the methane hydrate-bearing clay, it is found that its strength envelope presents typical nonlinear characteristics.