The invention belongs to the technical field of aluminum profile processing and relates to automatic loading and position adjusting mechanisms for jaws of an aluminum profile straightening machine. Two U-shaped jaws with opposite openings are mounted on a rack; at least one U-shaped jaw is connected with a drive cylinder driving the U-shaped jaw to move axially along an aluminum profile, loading and position adjusting mechanisms are fixedly mounted on the lower sides of the openings of the U-shaped jaws, a main connection base on each loading and position adjusting mechanism is fixedly mounted on the lower side of the opening of the corresponding U-shaped jaw, a lifting oil cylinder is fixedly mounted on each main connection base, a material support adjustment mechanism is connected on a cylinder rod head of each lifting oil cylinder and comprises two material support plates as well as a driving chain wheel and a driven chain wheel mounted between the two material support plates, a hydraulic motor driving each driving chain wheel to rotate is fixedly mounted on the corresponding material support plate, each driving chain wheel and the corresponding driven chain wheel are sleeved with a specially-made chain with external teeth, and the problem that a common loading lifting mechanism cannot slightly adjust relative position deviation, caused by profile deformation and other reasons, between supplied materials and jaws is solved.