Chashgui Gas Field is one of the gas fields supplying gas to the Central Asia Natural Gas Pipeline. Limited by the low coring recovery rate and low drilling success ratio in early period, the reservoir characteristics of Callovian Oxfordian in Chashgui area is unclear, which causes difficulty in exploration evaluation and gas field development. Based on petrology analysis of the core data, slice arbitration, core physical property and pore structure, and combined with the previous achievements, this paper studied the characteristics of Callovian-Oxfordian reservoir in Chashgui Gas Field. The result shows that the reservoir property is middle to low porosity and low permeability, and the reservoir is mainly of middle to small pore and small throat. The reservoir in this area was divided into 3 types, and the characteristics of each type of reservoir were studied. The rock type, sedimentary facies and diagenesis have important effect on the reservoir development. These recognitions can provide basis for the evaluation and development of the gas field, and provide reference for the progressive exploration in surrounding area.