In this paper, the inhibiting effect of organic silane waterproofing membrane on the capillary water rise height (CRH) of roadbed soil has been investigated, and the pore characteristics of the waterproof membrane have been studied. Different tests were performed to validate the resulting performance, such as CRH, contact angle (CA), and mercury intrusion porosimetry (MIP). The results showed that at 92 % compaction degree, the consumption of organic silane per unit area (OSA) of 8 g/m2 to 15 g/m2 could effectively inhibit the CRH. The CA of the waterproof membrane increased with OSA consumption and compaction degree. When the compaction degree and OSA consumption increased, the large pores were divided into small pores, resulting in a decrease in the most probable pore size of the waterproof membrane and an increase in the cumulative mesopore volume. Additionally, the specific surface area of the pores and the roughness of the pore surface of the waterproof membrane increased, the pore structure became more complex, and the fractal dimension was closer to 3.