According to the hot topics of the natural gas hydrate distribution regularity,formation conditions,accumulation process and accumulation pattern, gas hydrates reservoir forming conditions including gas source, gas hydrate stability zone, reservoir stratum, water source and migration passage were summarized by literature review first. Then, three main factors, geological structure condition, sedimentary condition and geographical climate change were summarized and analyzed, which control the accumulation and distribution of gas hydrates. On basis of this,basic concepts and research methods of natural gas hydrate petroleum system were analyzed and discussed by the example of gas hydrate accumulation conditions and process in permafrost regions of Kunlun mountain pass. The results show that the key of studying gas hydrate accumulation process and evaluating gas hydrate reservoir forming potential is analyzing how the static accumulation elements couple and match in geological time and space.