Taking a project for example, this paper analyzes the uneven settlement of dam at different dissolution degrees of dam base rock mass. The paper uses a three-dimensional numerical analysis. The result of calculation can show the following findings: the maximum displacement on dam top will be 10 cm if a strong dissolution occurs at dam base. The maximum displacement on dam top will be 5.5 cm if a middling dissolution occurs at dam base. The maximum displacement on dam top will be 4 cm if a slight dissolution occurs at dam base. The more serious of dam base dissolution, the more serious degree of uneven settlement in dam.