Abstract: Abstract: In order to reduce the decay of the droplet carrying capacity and increase the droplet coverage on hidden area of the foliage, a double air-assisted electrostatic spraying system which included anelectrostatic nozzle, a centrifugal blower, an axial fan and a diaphragm pump was proposed in this study. The power of double air-assisted electrostatic orchard sprayer was from power take off (PTO) of tractor to drive hydraulic pump (CBH-G563-AFHL).There were three hydro-motors in hydraulic system to drive centrifugal blower, axial fan and diaphragm pump separately. The indoor and outdoor tests including charge to mass (CTM), air velocity distribution, vertical distribution of spray volume and canopy droplet coverage was conducted. The faraday cylinder was used to collect spray volume, Key sight 34410A digital multi-meter was used to test current, and the CTM was calculated. The result showed the CTM at 0.2 m was reached to 1.0 mC/kg with damping along air direction, but the current could also be tested at 1.8m. The air velocity distribution, vertical distribution of spray volume was based canopy biomass of spindle type fruit, the two maximum heights were between 0.5 and 1.5 m. The field experiment was carried out in Shanxi during October 14 to 16, 2015. The objective of this experiment was to evaluate the effect of electrostatic charge on foliar spray deposition in a high spindle apple orchard using the double air-assisted electrostatic sprayer. The temperature was 25 ℃, relative humidity was 55%. Experiment plot was a modern standard apple orchard which was 350 m long and 200 m wide, the tree was spindle type apple fruit, three years older, 3.2 m in height, 3.5 m row spacing and 1 m spacing in the rows. Trimming was done every year after harvest. There are iron wires at 0.5,1.5 and 2.5 meters high which had different canopy width of 1.0, 0.6, and 0.3 m, and the foliage density was 7.8, 3.6, 1.97 m. The test was strictly followed the quality of air-assisted orchard sprayer (GB/T 24683—2009). The electrostatic system was switched on and off, in order to evaluate its effect on deposition on exposed and hidden face of the foliar. The flow rate at the nozzles was maintained unchanged across the tests, and the main environmental parameters were measured during the tests, they were air temperature, wind speed, and relative humidity. The water sensitive paper as collectors, the profile sampling strategy was adopted. The sprayer’s working velocity was set at 0.84 m/s, spraying pressure was 0.5 MPa, rotation rate of axial fan and centrifugal blower were 1 400 and 1 800 r/min. Each test condition was replicated three times in the same position. Experimental plot consisted of four adjacent rows sprayed under real conditions, i.e. by passing with the sprayer in all the three inter-rows; foliar sampling was carried out in the central inter-row. Blocks were separated by three unsprayed inter-rows in order to avoid possible overlapping due to spray drift. The test was conducted to determine effects of electrostatic spraying on hidden droplet coverage and droplet distribution on canopy. All statistical analysis and graphical representations were performed using Microsoft excel 2010. Results showed the droplet coverage on exposed and hidden foliage were 115 and 47 dot/cm2 at single spraying at the condition of the spray volume 3.5 L/min and driving velocity 0.84 m/s. This illustrated the single spraying was enough for insect prevention, and double spraying was suggest for preventing disease. The droplet coverage was improved 20% at the outside of tree closed to sprayer using electric spraying, while 7.2% was improved at the outside of tree away from sprayer at beyond. The research can provide technology support for air-assisted electric orchard sprayer designing and spraying standard setting.