Based on field observation and description, this article systematically analyzes the deformation mechanism of fracture in tight sandstone-gypsum mudstone reservoir-caprock combinations in Kuqa Depression, the researches show that deformation mechanism of faults in gypsum mudstone depends on the brittle-plastic characteristics which are controlled by burial depth. The gypsum mudstone under shallow burial depth lies in the brittle deformation phase and through-going faults which are filled with fault gouge can be formed with poor vertical sealing capacity; the gypsum mudstone under deep burial depth is in brittle-plastic deformation phase, it can form the smearing-type fault zones accompanied by increased throw, and smearing gradually loses continuity. Continuous gypsum rock smearing can form effective sealing. Once continuity is missing, hydrocarbon will be dispersed vertically through the cap rocks; the fractures cannot go through the strata which the gypsum mudstone under deep burial conditions lies in the plastic deformation phase. Therefore, both plastic and brittle-plastic gypsum mudstone can form effective sealing ability under the condition of continuous smearing. When the faults are deformed, the reservoirs have already been densified, uplifting and reservoir overpressure lead to the main fault deformation mechanism of ruptures, fault cores consist of fault breccia with lots of fractures developed in the fault zones, creating vertical migration pathways of hydrocarbon, and the lateral sealing ability relies on lithology juxtaposition. There are three typical characteristics of the gas accumulation mode sealed by lithology juxtaposition: firstly, the distribution of gas is closed to the regional caprock, in other words, the regional caprock is above the gas reservoir; secondly, the juxtaposition of regional caprock and reservoir form the effective trap, so the gas is mainly distributed in the uplifted wall of gas source faults; thirdly, the hydrocarbon column height depends on the size of throw, the minimum throw within the range of the trap determines the height of hydrocarbon column and the distribution of gas-water interface.