The ultra-deep gas reservoir in the Keshen Gasfield is characterized by complicated geological conditions，poor seismic data and great difficulty on gas reservoir description，making it a world-class challenge of exploration and development. To understand the characteristics of gas reservoir deeply，long distance multi-well and multi-azimuth interference well-testing was carried out in many gas reservoirs of Keshen Gasfield. Accurate multi-well interference data were acquired and verified by both positive and negative authentication. Approaches like extremal value analysis，investigation radius method and so on were employed to analyze the tested data，which was also compared with numerical simulation results based on the geologic study of the gas reservoirs. The results of investigation show that the interference signals in the developed area of Keshen2 gas reservoir are strong，indicating that the reservoir is highly connected with the well-developed natural fractures. Few faults or dominant fractures appear. The fracture permeability is above Darcy level. Obvious interference signals were detected between Keshen5 and Keshen11 gas reservoirs，which means that the two gas reservoirs are interconnected and proved to be the same one. Results from numerical simulation show that the connectivity in the west area is better than that in the east. This technology has realized quantitative analysis of fractured gas reservoir in Keshen Gasfield，which is of great significance for the effective exploration and development of ultra-depth，high-pressure and fractured tight sandstone gas reservoirs.