In view of the several poor atomization phenomena, such as drops, flowing liquid or larger fog group in the application of the pulsed smoker/fogger to spray pesticide, the 6HYW-60S pulsed smoker/fogger machine was improved to set the liquid medicine flow into an adjustable test device, with five throttle openings and four liquid flux. The air flow velocity and temperature before and after injection of pulse engine, as well as the droplet size distribution under each spraying condition were tested. The results showed that from the minimum throttle opening to the maximum throttle opening adjustable range, the corresponding pulse engine fuel consumption rate was changed in a small range, only causing a 13.0% relative change. The corresponding air temperature and speed in the nozzle was also changed to the same extent. When spraying, the temperature and velocity of the air flow at the nozzle had a very obvious change. The high temperature air flow of more than 700℃ without spraying fell to about 75℃, and the corresponding velocity of the air flow was decreased by about 16%. The opening of the throttle and the flow of liquid had little effect on the temperature, but the influence on the velocity of the droplet flow was very obvious. When the throttle opening was increased, the velocity of droplet flow was obviously increased, the liquid flux was increased, and the velocity of droplet flow was obviously decreased. Under the different throttle openings, the atomization effect of the minimum liquid flow rate of 20L/h was not good, especially in the vicinity of the tailpipe exit, there were a large number of droplets larger than 300μm. These droplets were easy to fall to the ground and cannot be effectively applied to the target. When the liquid flow rate was increased to 40L/h and above, the droplet volume diameter of each droplet was smaller and the average value of each position under the same working condition was less than 60μm. The droplet size distribution of thermal atomization was not a normal distribution with single peak value, and there were different droplet size groups, and the central droplet size of droplet groups was basically the same. The droplets on the central axis of the nozzle were fine and even atomized. The droplets on the central axis were slightly larger than those at the center point, but the droplets on the bottom of the nozzle was increased significantly. The farther the distance from the center axis was, the more obvious the droplets was increased, that was, the amount of larger fog droplets in the droplet stream was gradually increased. The flow rate of 60L/h and the throttle opening of 90° was the best atomization condition, and a good atomization effect was formed in the whole spraying area.