In order to realize frequent feeding in cattle farm, automatic charging system of forage push robot adopted upper docking type, and it included charging pile and charging control part of the robot. The charging pile included battery charger, charging circuit and charging electrode. The charging control part of robot included controller, walking driving module, power monitoring module, sensor data acquisition module, relay and charging electrode. A coordinate system XYZ was set up at the charging junction. According to electrode length, electrode compression stroke and electrode width, the fault tolerance range of X, Y and Z-axes was determined. According to the working environment of semi-open cattle farm, charging piles and magnetic stripe navigation charging path were set up in automatic charging area. During the navigation of forage pushing robot, magnetic navigation sensor detected magnetic signal, and magnetic navigation deviation was obtained by data processing. A fuzzy PID control was adopted. When the control speeds of the left and right wheels of the forage pushing robot was obtained, the speed value of each wheel was converted to angular velocity value of according motor. The controller outputed PWM signal of corresponding duty ratio to control the rotation speed of motor. Combining with the characteristic and experiment of magnetic navigation sensor, the adjustment rules of output parameters of fuzzy controller was obtained. The results of charging and docking tests by magnetic strip navigation were as follow. When the absolute value |e| of magnetic navigation deviation was the maximum, the maximum value of proportional coefficient adjustment value ΔKp was 1.28, and the minimum value was 1.03. The maximum value of the integral coefficient adjustment value ΔKi was 0.13, and the minimum value was 0.06. The maximum value of differential coefficient adjustment value ΔKd was －1.18, and the minimum value was －1.5. PID controller coefficient can be adaptively corrected by the fuzzy PID control. The maximum docking deviations of magnetic navigation on X-axis, Y-axis and Z-axis were 4.1cm, 1.9cm and 0.7cm, respectively, and the docking deviations were within the fault tolerance range.