Crawler-type tractors use differential steering, which has poor steering controllability and affects the performance of automatic navigation. In order to improve the performance of the automatic navigation of the crawler-type tractor, hydraulic transmission control planetary differential steering crawler-type tractor was taken as the research object, and the mathematical model of the turning radius of the crawler tractor was established. A calculation method for the mean and variance of the turning radius under each control variable was constructed, and a method for updating the mean and variance of the turning radius based on Kalman filter and local weighted regression was established. Based on Gaussian mixture model a tracked tractor turning radius control method was established for straight-line path tracking and turn round respectively. The pure pursuit was used to conduct automatic navigation simulation tests with different initial position deviations, and the results of navigation trajectory, position deviation and angle deviation were obtained. Using the NF-702 crawler-type tractor as experiment platform, a series of simulation tests were done at different speeds. Experiment results showed that when the initial heading angle was 0, the vehicle speed was 1.0m/s and 1.5m/s, the average navigation error was -0.62cm and 0.28cm, and the absolute value of the navigation error was 10.14cm and 8.10cm, respectively. The mean absolute value of navigation error was 2.34cm and 2.57cm, respectively, and the root mean square error of navigation was 3.77cm and 3.99cm, respectively. The experiment results showed that the proposed turning radius control method of crawler-type tractors based on Gaussian mixture model can be applied to the field of tracked tractor automatic navigation to meet the actual field operation requirements.