How to build a permanent anti-seepage system on a new dam to ensure stable inland waters has become a key concern. Taking an artificial island in a project as an example，this paper focuses on two construction techniques including reinforced concrete anti-seepage walls engaging with deep cement mixing piles and reinforced concrete anti-seepage walls engaging with steel sheet piles on a new dam，and it compares the two techniques in terms of the anti-seepage effect and economic benefits to select the appropriate construction scheme. The results show that：1）The construction scheme of using reinforced concrete anti-seepage walls to vertically engage permanent steel sheet piles on the new dam is economically feasible. 2）On the basis of reducing the construction difficulty，the anti-seepage system of the dam is strengthened，and the effect is obvious.