A lathe fixture for machining a hub is characterized in that a power chuck (10) is installed inside a base (5), a positioning connecting block (6) is installed on the power chuck (10), a fan-shaped claw (7) is installed on the positioning connecting block (6), a pressing block (18) is installed on the base (5), and a first support plate (16) is arranged; the shell (2) is arranged in a back cavity of the base (5) from bottom to top, the force transmission shaft (4) penetrates through the base (5), the force transmission rod (3) is fixedly arranged in a groove of the shell (2), the first support plate (16) and the second support plate (14) are respectively arranged at the front end and the rear end of the shell (2), the balance block (15) is fixed between the first support plate (16) and the second support plate (14) through two guide posts (17), the spring (13) is arranged in the groove of the balance block (15) and the second support plate (14), and the cover plate (1) is fixedly arranged at the lower end of the shell (2); the invention provides a clamp with a centrifugal force compensation mechanism.