In order to accurately monitor the happening of orchard fruit fly in large area, an orchard fruit fly monitoring system was designed based on the internet-of-things. The system is composed of intelligent fruit fly trap, monitoring terminal, remote terminal and mobile terminal. Several intelligent traps and monitoring terminals were installed into the orchard, forming a star style short-range wireless communication network. Fly happening information is gathered by the monitoring terminal and sent to either the remote terminal or the mobile terminal through the GSM/GPRS service. The intelligent fruit fly trap comprises a solar panel, bracket, trap enclosure and the functional circuits mounted inside the enclosure. The functional circuit includes the photoelectric detection circuit, the microcontroller, the short-range wireless communication module, and the lithium battery charging circuit. The fruit fly entering into the trap is detected using the low-cost and high-stability infrared photoelectric sensor. The monitoring terminal comprises a microcontroller, a short-range wireless communication module and a GSM/GPRS module. Both of the intelligent fruit fly trap and the monitoring terminals’ software were designed based onμC/OS-II real-time operating system. The results indicated that: the average operation current of the intelligent fruit fly trap is 97 mA, the operation current of the monitoring terminal with or without the GSM/GPRS module working is 60 mA or 328 mA, both of the equipments’ power consumption are lower than their battery power supply ability. The fruit fly monitoring accuracy of the system can reach 94.23%.