A comprehensive analysis of hydrocarbon accumulation conditions and typical reservoirs reveals that a large carbonate petroleum province is formed around the Manjiaer Depression in the Tarim Basin and it consists of Ordovician non-structural petroleum reservoirs. The special characteristics of carbonate reservoirs result in the wide and discontinuous distribution of irregular fracture-cavity hydrocarbon pools. The enrichment of hydrocarbon is controlled by reservoirs, which are the main controlling factors of the formation and distribution of the large petroleum province.