The influence of hydraulic fracturing problem of soil core wall dam on the safety of embankment dam has been paid great attention in engineering field. This paper analyzed the mechanism that hydraulic fracturing occurs in asphalt concrete core wall, and proposed that the horizontal seam produced in construction of compacted core wall's caused by “pine cone effect” and the low permeability of asphalt concrete are the important material conditions of hydraulic fracturing, while the “arch effect” and powerful “water wedge effect” produced by transition material and core wall interactions are the hydraulic fracture mechanics conditions. The analysis of examples proved that the soil core wall and the asphalt concrete core wall all exist the risk of hydraulic fracturing,which need to pay close attention in the field of water conservancy sector.It noted that high asphalt concrete core wall dam should be carefully studied and the core wall's impervious safety and reliability be evaluated. The result has a certain reference value for the design and construction of asphalt concrete core wall dam.