In order to improve the intelligent level of unmanned operation of tractor operating unit and realize the cooperative control of lateral movement, longitudinal movement and tool lifting operation of tractor operating unit, a cooperative control system for unmanned operation was designed. Taking the seeding operation unit as the research object, the unmanned operation cooperative control system of tractor unit was divided into planning layer, decision layer and execution layer. In combination with the agronomic requirements of seeding and the kinematics characteristics of the tractor operating unit, the planning layer used longitude/latitude coordinates to plan the operation path. In order to meet the path tracking of both the straight line segments operation area and the turning curve area, an adaptive preview path tracking control algorithm was proposed. Decision layer formulated the unmanned operation joint control strategy of tractor operating unit to realize the precise control of tractor-planter joint operation. Execution layer was used for hardware control design to the tractor steering, lifting, throttle, brake, clutch and other mechanisms. On this basis, the unmanned seeding operation simulation and field experiments were carried out respectively, and the simulation results verified the feasibility of the unmanned operation cooperative control system for tractor seeding unit. Field experiments showed that the steering, throttle, clutch, brake and tool lifting of the tractor worked together strictly according to the control instructions made by the planning layer and the decision layer. In the experiment process, the average error of steering control was 0.45°, the mean of lateral error of straight line segments was 0.035m, and the maximum of lateral error of turning section was 0.11m. The lifting response time was 1.2s, and the overshoot of lifting angle was less than 1.5°. Throttle, brake and clutch were all operated according to the decision instruction. Unmanned operation cooperative control system met the requirement of unmanned operation of tractor unit and provided technical support for unmanned farm.