Abstract: The size and space of droplets produced by the droplet generator affect the radiation and evaporation characteristics of the droplet layer, and the controllability of the size and space of the droplets deserves special attention. According to Weber’s jet instability correction equation, the dimensionless wave number and disturbance frequency range of uniform droplet flow were determined. Combined with the mass conservation of jet, the relationship between the dimensionless wave number and the size and space of droplets in uniform droplet flow were analyzed. The theoretical and experimental results were compared under different nozzle diameters and jet pressures, which verified the theoretical calculation results of droplet size and spacing, and provided a basis for the study of droplet layer radiation evaporation characteristics.