Abstract: Applying the gas-liquid two-phase flow spraying technology, and spraying the pesticide by a carrier of fog at normal temperature is a new technology to prevent the disease and insect in the protected agriculture operation. Which fogging characteristics are that the diameter of the fogging droplet is very fine with a long time of floating and suspending in the space. In this study, aiming at finding the rules of fog movement, distribution and deposition, after having sprayed the black liquid with high density in the space of plastic greenhouse, the quality density of pesticide in the greenhouse space was tested and analyzed by an atmosphere sampling apparatus and a spectrophotometer. The main parameters of describing the operation performance, technical characteristics and an economic and practical testing method for the pesticide fog, were obtained. The rule of the pesticide quality density in the greenhouse space changes with the length of the plastic greenhouse and time. And the rule of fog droplet deposition, was discovered. The study shows that the test method is simple and feasible, which has laid a foundation for analyzing the spraying fog flow site to get the optimum spraying option and evaluating the spraying quality and its effect.