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The high temperature in summer causes heat stress in dairy cows, spray cooling system is one of the most effective physical cooling technologies that is widely used in practice. The laser precipitation monitor (LPM ) was used to measure droplet size ,droplet velocity and intensity. Six kinds of standard fanshaped nozzles (9010, 9030, 9060, 9080, 90100, 90120) were measured with LPM under 0.15MPa, 0.20MPa, 0.25MPa pressures, the droplet distribution, the relationship of droplet diameter and spray flow, single droplet kinetic energy, spray intensity was analyzed. The results show that: the droplet distribution normally distributed model and average droplet diameter are ranged from 0.475mm to 1.210mm under 0.15MPa, 0.20MPa, 0.25MPa pressures of six different nozzles. Droplet diameter has a linear relation with spray flow (R2>0.96). 15%~20% of droplet diameters within 0.125~0.250mm were sprayed by nozzles of 9010 and 9030 type, which make it easy to drift but not suitable for cows evaporative cooling. The single droplet kinetic energy along with the water droplets was increased with the increase of droplet diameter under three different working pressures, showing a power relationship (R2>096). The mean nozzle spray intensity and mean droplet diameter show an exponential relationship (R2>096). The average intensities of spray were all greater than 72mm/h, which satisfied the purpose of cows spray cooling system. The experiment concluded that the average drop particle diameter are 0.801mm (9060), 0.914mm (9080), 1.047mm (90100) and 1.210mm (90120), which could cool cow from 39.3℃to 37℃, using 85s, 75s, 48s and 30s, respectively.