The existing field spraying system mainly control spray volume by the variable-rate technology, which is lack of pesticide spraying data remote monitoring and traceability management. A precision variable-rate monitoring and control system was designed based on pesticide spraying traceability. The system can realize precision variable-rate spraying, on-line monitor and real-time display different spray information, including spray plot, spray time, spray area, type and ratio of pesticide, spray volume, spray pressure, real-time spray flow and spray speed, which can be used to pesticide spraying traceability management. Based on the system, the tests of spray volume calculation accuracy, spray area calculation accuracy, data transmission stability of Internet of things, dynamic response of variable-rate control system, variable control precision and pesticide spraying uniformity were carried out respectively. The test results showed that the maximum error of Beidou positioning speed measurement was 1.33% and the mean error was 0.82%, the calculation error of spray volume was 1.73%, the calculation error of spray area was 2.61%, the data loss rate was 3.51%, the system stability adjustment time under continuous speed change was 4~5s, the variable-rate regulation accuracy was 245%, the density of droplet deposition was greater than 20 drops/cm2, and the variation coefficient of spray coverage in sprayer walking and spray direction was less than 10%, which met the operation requirements of precision variable-rate spray. The research can realize the traceability management of the pesticide spraying data under the precision variable-rate adjustment of spray volume, and provide support for the pesticide residue risk assessment in field crops.