Abstract: Clay core wall earth-rock dam is one of the most widely used types of dams in China. It has advantages such as strong adaptability to foundation deformation, low requirements for geological conditions, on-site material sourcing, and low cost. However, due to its structural characteristics, the rockfill dam is prone to seepage problems, and seepage failure is the main cause of instability and damage. The core wall, as an impermeable barrier, may have high permeability areas due to quality issues or improper construction methods. These high permeability areas can lead to seepage failure in the dam body and pose a threat to dam safety. Taking a clay core rockfill dam in a certain location in Heilongjiang Province as a research model, two dimensional finite element numerical simulation technology and big data statistical analysis methods were used to study the influence of high permeability areas in the core wall on the seepage field of the rockfill dam. The results showed that high permeability areas significantly increased leakage rate and volume of water through the dam body,raised the elevation of flow outlet points from the core wall, and increased local pore water pressure affecting the downstream seepage field. As the position of high permeability areas increased, leakage volume gradually decreased while flow outlet point elevation from the core wall gradually lowered. At the same time, there was an increase in pore water pressure area affecting both single-width leakage volume and flow outlet point elevation from the core wall. When the position of high permeability areas was at a distance of 2, 7, 12 and 17 m from the dam base, respectively, the pore pressure in that area was elevated by about 18%, 50%, 60% or more than 90%. When the permeability coefficient of highlypermeable area increased, the area with elevated pore water pressure in the intermediate-highlypermeable area tended to shrink. The research results could be used for seepage inversion analysis and dynamic safety monitoring and evaluation based on dam monitoring data in the future, so as to ensure the continuity of dam control in the whole life cycle and improve the safety of dam.