A flow-altering armoring countermeasure device, frames in the shape of tetrahedrons, was tested by destructive tests and scour tests in a laboratory flume. Destruction development process and relationship between the friction velocity and layer parameters in critical destabilization condition of tetrahedral frames were investigated by destructive tests. Erosion and deposition characteristics near the frames were studied by scour tests. The destructive tests show that the frames stabilities are associated with layout form and parameters. The streamlined arrangement may be good for the frames stabilities. Under critical destabilization condition, friction velocity increases with increasing the layout-density of frames. As the ratio of flow-depth to frame-layer-thickness increases, the friction velocity increases and then becomes stable when the ratio is larger than 4. The scour tests indicate that unlike the riprap layer, the scour positions are moved backward in the edges of frames. The above phenomena and sedimentation inside the frames are conducive to frames stabilities. The protected object could be placed in this sedimentation area to achieve better protective effect.