Field tests are necessary in establishing navigation models and algorithms for agricultural vehicle robots. And it costs much to use tractors or combine harvesters as the platform in terms of system modification, routine maintenance and fuel consumption. The objective of this research was to develop a general-purpose test platform for conducting experiments in agricultural autonomous navigation at a low cost based on a commercially available electric vehicle. A brushless motor was utilized as the power source for automatic steering. An analog PID controller was designed to compare steering commands and actual steering angle and calculate an appropriate voltage signal as the input of the motor driver. A rotary encoder was attached to the driving wheel and a digital PID controller was implemented to determine the throttle value in real-time in maintaining the test platform at a desired speed. A CAN-bus network was established to integrate the automatic steering system and the speed control system as two nodes for information communication. And a CAN node interface was reserved for receiving commands from autonomous navigation systems to be evaluated. Field tests showed that RMS errors were 2.6 cm and 0.054 m·s-1 for lateral offset and speed control, respectively, in tracking straight paths, which indicated that the newly developed test platform met requirements for agricultural navigation experiments.