By the software FLOW-3D，a three-dimensional（3D）numerical wave pool is constructed by the combination of the piston-type wave generation and the pore wave absorption to study the wave force on the vertical breakwater when the wave direction and the sloping wall change at a small angle（less than or equal to 15°）. The following conclusions can be drawn by the numerical simulation：1）For the wave force at the measuring points on the wall，it has a similar trend to the wave direction at all slopes of the breakwater and among all measuring points，and it reaches the maximum at a wave direction of 90°. 2）At the same slope of the breakwater，the variation trend of wave force with the wave direction among all measuring points at the bottom of the wall is not the same，and the slope of the breakwater can affect the variation trend. 3）The distribution of wave force on the wall is basically the same regardless of the slope of the breakwater or the action of any wave direction. 4）The distribution of wave force at the bottom of the wall is approximately trapezoidal. 5）In most wave directions，the maximum wave force at the measuring points on the wall and at the bottom of the wall occurs when the breakwater has a certain slope.