86%。Based on CAN bus and ISO11783 protocol, a direct injection variable-rate sprayer based on the prescription map was developed with the goal of realizing precision pesticide application and improving pesticide application efficiency. The spraying uniformity and accuracy of the direct injection variable-rate sprayer was analyzed through the comparison experiments between constant-rate spraying and variable-rate spraying. The field experiments showed that the spraying variable coefficient was below 10%. On a given field, the area, on which the spray volume difference between the actual spray volume and the volume supposed was less than 15%, was up to 86% of the total.