Abstract: The anti-seepage structure composed of cohesive soil is susceptible to local or vertical through-cracks as a result of the arching effect and uneven settlement. These cracks may trigger concentrated seepage erosion, thereby posing a threat to the safety of the dam structure. This paper selects remolded clay as the research subject and pre-fabricates vertical non-through and through cracks to mimic the cracking phenomenon of the dam body. The RST-300 multifunctional seepage piping test instrument is employed to investigate the influence of crack location, opening size, and filter gradation on the seepage deformation of the anti-seepage structure. The seepage flow, pore pressure, and turbidity of the seepage water are concurrently monitored to ascertain the self - healing or erosion failure state of the cracks. Results indicate that under appropriate filter gradation, non-through cracks with an opening size of ≤3 mm can self-heal through particle deposition within the crack, and the self-healing characteristics are associated with the relative position of the crack and the crack - free soil. Through cracks with an opening size of ≤3 mm are capable of self-healing, whereas those with an opening size >3 mm will be regulated by the filter gradation and are prone to layer-by-layer cracking, fork-shaped or step-shaped failure. During the seepage process of cracked clay, the critical condition for soil particles to pass through the filter gradation varies dynamically with the hydraulic gradient, and the filter criterion needs to be transformed from a single geometric condition to a geometric-hydraulic coupling condition.