The invention discloses a mechanical 180-degree steering device for a linear motion process of an object. A driving device is used for driving a rotating device to move on a steering track plate, a first steering track and a second steering track are arranged on the steering track plate, two first arc-shaped bulging teeth are arranged at the middle section of the first steering track, and a secondarc-shaped bulging tooth is arranged at the middle section of the second steering track; in the rotating device, three bearings correspond to the first steering track, two bearings correspond to thesecond steering track, three mounting plates, five bearings and a main rotating shaft are assembled together and connected with a bearing bush through another bearings, and the bearing bush is connected with the driving device. By means of the steering track plate and the rotating device which are matched with each other, the 180-degree steering function in the linear motion process is realized bya fully-mechanical structure, and the requirements of higher linear motion speed, shorter linear motion distance and high 180-degree steering precision can be met simultaneously.