The invention discloses a tibia osteotomy positioning system and an ankle mortise working platform and an osteotomy plate fixing platform. The osteotomy plate fixing platform comprises an osteotomy working platform, an osteotomy plate and a laser device, wherein an adjustable angle is formed between the osteotomy plate and the osteotomy working platform, the laser device is arranged on the lower surface of the osteotomy working platform, and the laser device is a laser transmitter or a laser rangefinder. Laser alignment principle and a beam splitter prism are adopted to determine a reclining angle between the working planes of the osteotomy plate and an ankle holding device. The tibia osteotomy positioning system and the osteotomy plate fixing platform and the ankle mortise working platform improve alignment accuracy, simplify operation, improve operation efficiency, and reduce burden of doctors and patients.