Natural gas hydrate may be closely related with conventional hydrocarbon resources in time and space. In some appropriate conditions, natural gas hydrate can accumulate along with or coexist with conventional hydrocarbon in relative reservoirs. On the base of this research, three kinds of basic accumulation coexistence models are suggested, which are the leaking accumulation, the capping accumulation and the capping side-accumulation coexistence models. The Leaking accumulation coexistence model means that conventional hydrocarbon has accumulated first in lower reservoirs and then leaks up to form gas hydrate in upper reservoirs, which is characteristic of a complete source-reservoir-caprock assemblage under the gas hydrate reservoirs. The capping accumulation coexistence model refers that gas hydrate accumulates in upper reservoirs and meanwhile the gas hydrate reservoirs act as the cap rocks of the lower conventional hydrocarbon reservoirs, which is characterized by a nice source-reservoir assemblage but lack of capsealing condition. The capping side-accumulation coexistence model implies that due to covering of the upper gas hydrate reservoirs, the lower hydrocarbon has been barriered as it migrate up and accumulate side away into the adjacent reservoirs. Actual hydrocarbon accumulation may be any assembled pattern among these models.