Abstract: The strong heterogeneity, unclear controlling factors and reservoir accumulation rules of the Carboniferous inside-type volcanic reservoir constrain its exploration in Xiquan area of eastern Junggar basin. Based on the data of geophysical prospecting, geology and drilling, the paper studies the characteristics of the Carboniferous inside-type volcanic reservoir in Xiquan area. The inside-type volcanic reservoir in the study area is characterized by low porosity, low permeability and strong heterogeneity, which belongs to fracture-pore reservoirs. The study shows that lithology and lithofacies are the basis for high-quality reservoir forming, the development degree of fractures is an important factor affecting the physical property and effectiveness of the reservoir, and dissolution can improve the physical properties of the Carboniferous inside-type volcanic reservoir. Based on the configuration relationships between hydrocarbon source rocks and reservoirs, 3 hydrocarbon accumulation models of the Carboniferous volcanic rocks in the study area are established—the reservoir of weathering crust type is mainly developed in Batamayineishan formation; 2 kinds of inside-type gas reservoirs are found in Songkaersu formation, i.e., the lithological gas reservoirs in the b member of Songkaersu formation and the structural oil and gas reservoirs in the a member of Songkaersu formation. The shallow Carboniferous strata with high exploration degree are the areas where oil reservoirs are developed, and the deep slope zones are the favorable areas for natural gas exploration which has good prospecting potential and low exploration degree