An automatic steering control system of friction drive for tractor was designed to solve the problem that traditional automatic steering control system was too complex to be installed on 2BFQ-6 type direct seeding combined dual purpose planter. A four connecting rods parallel institutions was used to develop the steering control device of friction drive for achieving fast mode switching. Meanwhile, the friction drive was simple in operation and convenient in installation by using the clamping installation method. The discrete simulation model of tire steering maneuver was established based on slip characteristics of the device. The simulation model was adopted to design the genetic algorithm optimizer, which could optimize the controller parameters online. The selfadaptation controller was adapted to control the automatic steering device of friction drive. The experiment on LX854-DFH tractor was used to analyze the performance of genetic algorithm optimizer. The experimental results showed that rise and regulation response time of the genetic algorithm optimization controller was decreased by 15% and 29% compared with the fixed parameter controller, respectively. The measured 20°step responses indicated that the average regulation time was 2.4s, the average absolute steadystate error was 0.197°, and there was no steady state oscillation, when the experimental results were recorded. The automatic steering control system of friction drive could be applied to control nosewheel steering turning of 2BFQ-6 type directseeding combined dual purpose planter for rapeseed.