The spray deposit distribution model was established by way of theoretical analysis and experimental research, and the law of spray deposit distribution was studied. The result showed that the CV (coefficient of variation) value of boom direction at the middle point on the boom between two adjacent nozzles was reduced dramatically. The CV reached its maximum value close to the center of the pattern, directly under the nozzle. The CV value of advancing direction has a periodic change with the cyclic of the duty cycle. Under the same pressure, both boom and advancing direction CV would rise with the acceleration of the tractor and would fall with the increasing of both duty cycle and nozzles height in the researched range (40～60 cm). The flat fan nozzle of 110° would give more uniform deposit distribution than that of 80° at the same advancing speed and duty cycle.