The Hashan area in the northwestern margin of Junggar Basin is a complex piedmont tectonic belt，in which the Carboniferous volcanic nappe forming in the continental margin island arc is an important oil and gas reservoir in this area.To understand the volcanic reservoir development characteristics and control factors in the complex tectonic belt，using a large number of outcrops，core，thin section，scanning electron microscopy and imaging logging analysis data，the characteristics of volcanic reservoir，influencing factors and accumulating model were studied. The results show that the carboniferous volcanic rock is mainly composed of 2 types and 5 kinds of lithology，including lava（basalt，andesite，and basaltic-andesite）and volcaniclastic rocks（volcanic breccia and tuff）. Lithology and lithofacies are the internal factors influencing volcanic reservoirs development，while weathering and leaching and tectonism are the external factors. The genetic types of reservoirs include the lithofacies-fault type and the lithofacies-fold type. The volcanic breccia，tuff and andesite developing at the front wing and core of nappe，and weathering crust of faults intersection，and eruption cycle boundary are favorable distribution areas of volcanic reservoirs.