The measurement of the size of the atomized field is of great significance for testing and evaluating the spray performance. It is very important to summarize and analyze the technical means of optical particle size measurement. Firstly, the basic principle of spray and mathematical representation of particle size are introduced. The principles and characteristics of the mainstream and emerging optical methods of particle size measurement, such as light scattering, structured laser illumination planar imaging, phase Doppler analyzer, laser holography and dual spectral imaging, are discussed in detail. At the same time, the typical applications of these testing methods are listed. On this basis, the problems existing in the spray field test are summarized and compared respectively, and the specific suggestions on how to select the test method properly are put forward.