Abstract: Using the joint testing device of soil-water-force characteristics of natural gas hydrate built by the project team, the sediment samples of natural gas hydrate were prepared by gas-rich method, and the effect of compactness on the mechanical properties of hydrate-bearing soil was studied by triaxial compression test. The test results show that the compactness has a significant effect on the stress-strain curve, stiffness and strength of hydrate-bearing soil, and strain softening occurs in high-density hydrate-bearing soil under low net confining pressure. on the other hand, the hydrate soil with medium or low density appears strain hardening, and the degree of shear thinning decreases with the increase of compactness. The stiffness of hydrate-bearing soil will increase with the increase of compactness, and this enhancement effect will gradually decrease with the increase of net confining pressure; in the case of higher density, more hydrate exhists in the cementation mode, however shearing tends to break more hydrate. Both affect the strength of hydrate-bearing soil. Therefore, the strength of hydrate-bearing soil is the highest in the case of medium density.