The invention provides a mechanical bent-plate-type slope adjusting clamp and method. The mechanical bent-plate-type slope adjusting clamp comprises a clamp base, wherein a side vertical plate and a middle vertical plate are arranged on the clamp base; a plurality of T-shaped grooves are formed in the outer side surface of the middle vertical plate from top to bottom in a spacing manner; a V-shaped positioning block is arranged at the bottom of the middle vertical plate; two raised brackets are horizontally arranged on the inner side surface of the middle vertical plate in a spacing manner; aservo motor is arranged on the outer side surface of the side vertical plate and connected with a worm; the worm is connected with a worm gear; an angle displayer is arranged at the tail end of the worm; one end of a gear shaft is mounted on the worm gear; the other end of the gear shaft penetrates through the side vertical plate and is mounted on the clamp base; the raised brackets are in hingedconnection with a rotating table plate through a hinge shaft; a fan-shaped gear is arranged on the reverse side of the rotating table plate and in meshed connection with the gear shaft; the T-shaped grooves are formed in the obverse side of the rotating table plate from top to bottom; and the V-shaped positioning blocks are arranged at the bottom of the rotating table plate. The mechanical bent-plate-type slope adjusting clamp and method have the advantages that the structure is stable, the rigidity is high, the operation is simple, the labor intensity is reduced, the working efficiency is improved, and the clamped part slope adjusting and positioning precision is high.