In order to solve the problems of sampling technology in spraying, a new measurement method of using micrograph combining with digital image processing technology for spraying deposition parameters analysis and sample in airtight space was given. With this method, the parameters of spraying deposition in entire spraying field could be analyzed, such as spraying coverage, droplets density, spraying uniformity and etc. During the experiment, it was found that with the increasing distance, droplet spraying coverage rose firstly and then declined, but the droplets density was of the opposite trend. The spraying coverage and droplets density would not change at the height of 0.4～0.8m on the ground. It is feasible to describe the droplets deposition in the spraying field by using the spraying coverage, droplets density and spraying uniformity.