<p>In the process of shale gas development by multi-stage fracturing, a large amount of liquid invaded the shale and destruct the seepage space of shale, thus affecting the seepage capacity of shale. A better understanding of the mechanism of liquid invasion on shale is crucial for drilling and fracturing design. This paper presented a series of experiments to comprehend the dynamic changes of microstructure and permeability after liquids invaded into shale. The results demonstrated that deionized water exhibits the highest infiltration volume, while slick water and kerosene exhibit similar levels of infiltration. Both deionized water and slick water exhibit an initial rapid decreased in shale permeability during the initial phase of liquid infiltration, followed by a fluctuation period where permeability initially increased and then decreased. The mechanism of liquid invasion on shale was discussed. Results show that the effect of liquid invasion on shale can be categorized into three stages. In stage 1, a limited number of micro-cracks formed in this stage and a lot of sticky flocculent minerals generated after immersed, leading to a significant decrease in the permeability of the shale samples. In stage 2, the uneven expansion caused by the hydration of clay minerals resulted in hydration stress directly applied to the tips of pre-existing micro-cracks, and lead to new cracks initiate and existing cracks propagate. In stage 3, over a certain period of hydration, isolated micro-cracks in localized regions of the shale merged and formed macroscopic cracks that traversed the shale. This study is helpful to understand the dynamic changes of shale microstructure and permeability after liquid invaded into shale.</p>