Abstract: Abstract: Citrus and other fruit trees in southern China are mostly on planted mountain hills. And, mountain orchard planting industry is a pillar industry for farmers in the south of China, but the mountain road construction is difficult. It is difficult to form a more perfect transportation network, which makes regular transporter difficult to be used widely in the environment. In recent years, China's mountain orchard mechanization process is accelerated. And, some of the transport machines, which are used in mountain orchards, were invented by numerous scientific research institutions. The use of these machines greatly increases the efficiency of fruit transport and reduces the labor costs. Among these machines, the mountain orchard monorail transporter machine is widely used in mountain orchards because of its simple structure, good economy, flexible laying track and minimal destruction of orchard terrain, good ductility and no influence from terrain factors. Mountain orchards monorail transporter machines mostly use batteries as energy, and have the maximum load of 200 kg, the operating speed of 0.3-1.2 m/s, and the maximum climbing angle of 30°. And this kind of mountain orchards monorail transporter uses worm gear as the main transmission mechanism. But the worm gear mechanism's mechanical efficiency is low. To solve downhill speed control problem of battery drive monorail transporter for mountainous orchard, monorail transporter drive system was designed for mountainous orchard. That was based on worm gear and consisted of dual-drive chain. The electric motor was used as a power source in this system, and the power was delivered by two-way parallel and independent transmission chain, in which one was based on worm gear and the other was based on chain transmission. According to the motion state of transporter, the electromagnetic clutch was controlled by using STM32 embedded control program. This paper explained the system's transmission principle, and important parts designed, and had detailed analysis on mechanical transmission efficiency. And, the output torque, the output power and speed of the system were obtained by using power flow analysis. The experiment was carried out under no-load and full-load condition. The operating speed was measured by STM32 combined with rotary encoder. The load was measured by tension sensor. The results indicate that, in the uphill operation, the output torque of the system is 44.352 N·m, the output angular velocity is 13.738 rad/s, and the output power is 609.31 W. And, in the downhill operation, the output torque of the system is 105.760 N·m, the output angular velocity is 4.608 rad/s, and the output power is 487.342 W. The system combines the advantages of the high efficiency of chain drives and the self-locking performance of worm gear, and has the characteristics of high efficiency, high safety, and controllability. Monorail transporter equipped with this system can run on the ground and uphill efficiently, and park anywhere on the slope and restart, and downhill speed can be controlled. Efficiency calculation result shows that theoretical mechanical efficiency of the system running on the flat and hillside is 81.2%, and the theoretical mechanical efficiency is 60.5% in the process of downhill running and reverse running.