Aiming at the risk of water inflow in the evaluation of hydrogeological conditions for coal gasification projects, combining with the hydrogeological conditions of a research area in northern Xinjiang, we analyzed the water source of the gasification cavity, studied the safety thickness standard of the aquiclude in the roof and floor of the gasification coal seam, and discussed the combination characteristics of the floor aquifer/ aquiclude and the gasification safety. The results show that the hydrogeological conditions in the study area are generally favorable for underground coal gasification, and the internal water inflow is 0. 27 m³ / t, which poses a very limited threat to the safety production of the gasification cavity. In the case of no fresh water recharge in the surface or underground outcrop area, the external water in the roof and floor aquifer of the gasification coal seam is main influence factor. Combining with the previous research results and the conditions in this study area, it is relatively safe when the roof aquiclude thickness is over 36 m, and it is basically safe when the thickness is over 42 m; It is relatively safe when the floor aquiclude thickness is over 20 m, and it is basically safe when the thickness is over 30 m. It is concluded that the coal measure aquifer will not pose a threat to the safety of the gasification cavity in underground gasification at most of the well points in the study area. When the thickness of the floor aquiclude combination is less than 30 m and the thickness of the floor aquifer is greater than 30 m, the water inflow of the gasification cavity may exceed the safe value.