A fixed chain engine braking device includes a brake box, a driving mechanism and a braking mechanism. One upright blind hole and one horizontal blind hole are placed in the brake box, and the upright blind hole intersects the horizontal blind hole orthogonally. The driving mechanism includes a rolling ball and/or a driving piston placed in the horizontal blind hole, the braking mechanism includes a braking plunger placed in the upright blind hole. A fluid passage is placed in the brake box, and the fluid passage is communicated with the entry of the horizontal blind hole.