<p>This study utilizes a coupled computational fluid dynamics and distinct element method (CFD-DEM) to analyze the suffusion behaviors of the grain-cementing type methane hydrate-bearing sediments (MHBS) under different methane hydrate (MH) saturations and environmental conditions. MH bonds existing in the MHBS sample were synthetize by using thermo-hydro-mechanical-chemical (THMC) contact bond model, which accounts for the influences of ambient temperature, pore water pressure, and salinity on the MH behavior. A comprehensive series of suffusion tests is performed under various hydraulic heads to investigate the impact of MH saturation and environmental conditions on the suffusion behaviors of MHBS. The results demonstrate that the breakage of MH bonds between fine and coarse particles is a fundamental prerequisite for the migration of fine particles. Both the cumulative fine mass loss ratio and the bond breakage ratio are two important factors in determining the critical hydraulic gradient of MHBS, which increases as MH saturation or the value of condition parameter increases. Besides, the void ratio variation during suffusion of MHBS is influenced by both the particle migration and the hydraulic gradient. Finally, this study presents the permeability coefficient equation and erosion law for MHBS suffusion, which incorporate important parameters related to MH, such as MH saturation, bond breakage ratio, and the condition parameter.</p> Graphical Abstract <p></p>