The effective development of shale gas depends on the generation of artificial cracks, and the continuous and efficient development of shale gas requires proppant to maintain the effect of artificial cracks. At the same time, to ensure the efficient development of shale gas, the conductivity of artificial fracture network must be maintained. At present, the microscopic mechanism of damage to the fracture conductivity of shale reservoirs is still unclear. In this paper, the marine shale in southern China is taken as the research object, and the experiment of rock plate diversion ability damage is carried out, and compared with tight sandstone and conventional sandstone, the variation law of the conductivity of fracturing fluid during the injection process is analyzed. The results show that with the continuous injection of the fracturing fluid, a large amount of proppant is gradually embedded in the crack, causing the conductivity to decrease. The initial diversion capacity decreased rapidly, and the subsequent deceleration gradually slowed down. The degree of damage of the conductivity of the marine shale support crack is much higher than that of the conventional reservoir. The damage rate of conventional reservoir support fracture conductivity is about 18%, while the damage rate of support fracture conductivity of marine shale is about 47%~85%. The rate of damage to the conductivity is closely related to the content and type of clay minerals. With the increase of clay mineral content, the damage rate of the conductivity is rapidly increased, especially the presence of illite and Yimeng can significantly improve the damage rate of the conductivity. Clay minerals have a strong ability to absorb water and swell, which tends to cause softening and creep strengthening of the surface of the supporting cracks, resulting in a decrease in proppant embedding and conductivity. In this paper, the shale conductivity experiment is used to analyze the variation of the conductivity of the fracturing fluid and the influence of the clay mineral content on the damage rate of the conductivity. In order to optimize the fracturing fluid formulation, improve the shale gas well drainage system and It is important to increase the output of shale gas.