In order to solve the unreliable problem of the v-belt drive of the gear pump in tomato harvester，the transmission device of circular arc tooth synchronous belt of tomato harvester gear pump was designed. The selection and design calculation of synchronous belt pulley, the analysis and design of the tension device and calculation of tension was carried out. The no load test of the whole machine shows that: the arc tooth belt transmission of tomato harvester gear pump worked smoothly and reliably, the belt vibration was relatively small, the belt temperature was normal, the oil cylinder, motor and brake ran well, and the structure design was reasonable. The device can satisfy the work requirements of tomato harvester gear pump.