The invention provides a wedge-shaped wave absorbing device with characteristic of freely changing an angle. The wedge-shaped wave absorbing device comprises slide rails, rotating handles, sliding blocks, fixed pulleys, connecting ropes, small pulleys, hooks, wave-absorbing plates and a vertical plate. The vertical positions of the wave-absorbing plates are adjusted by sliding the sliding blocks;and the rotating handles are adjusted to change the lengths of the connecting ropes, so that the angles of the wave-absorbing plates are adjusted. Therefore, a technical problem that the internal solitary waves with different scales under different water depths can not be eliminated in the prior art is solved.