To improve the quantity of droplets deposition and reduce the quantity of pesticide in the orchard on small fruit tree or sparse orchard, a track selfpropelled orchard sprayer was designed by combining the air-blast spray with internet of things technology. The machine was composed of mechanical frame, control system, power, walking system, transmission system and airblast spray system. The control system was made up of ultrasonic sensors, microcomputer control layer, WiFi wireless transport layer and mobile phone. The mobile phone can show some spray reference and send instructions to microcomputer. Experiment result showed that the quantity of droplets deposition was increased by 34.57% when the airassisted sprayer was used, the variation coefficient was reduced by 13.39 percent points, and compared with continuous spray, automatic target spray could save pesticide by more than 30%. The fan driving airflow of airblast sprayer improved droplets adhesion ratio on target and droplet distribution uniformity. The intermittent spraying was realized by ultrasonic sensors detection of effective target and control system processing spraying status parameters on-line, pesticide utilization was saved and residues were reduced. The machine had advantages of small size, convenient operation and good passing ability, which satisfied the need of plant protection work of low and short orchard.