Gas hydrate can exist in certain temperature and pressure conditions as solid form, but because of its special thermal physical and mechanical properties, it is impossible to be developed with "mining" type like other solid mineral resources. Under the present condition, drilling technology is the key for the exploitation of gas hydrate; it is economically feasible and can avoid the environmental problems that might be brought by mining. Based on the situation that gas hydrate was converted to the controlled resource underground before mining, mining mode combining chemical grout injection with depression was proposed.