An automated guidance system for tracked combine harvesters had been developed. A kinematics model for the harvester is constructed. A conventional and a X-turn path planning methods were provided. The system was successfully controlled speed, direction, and header of 2 modified harvesters, which had harvested 16 acres of rice land in December of 2015 and 2016. Results showed these machines can accurately cut along the edge of the cut/uncut, and cut all crops in every working path. The lateral offset is less than 5 cm in row following stage. In future, cutter, threshing roller, and other important working parts must be monitored to realize unmanned technology.