Objective To study the effect of relatively closed environment dispensing mode on insoluble particles in pharmaceuticals. Methods The numbers of insoluble particles in conventional manual dispensing mode and relatively closed environment dispensing mode in lass Ⅰ and class Ⅲ environment were detected, effect of different dispensing modes on the number of insoluble particles in pharmaceuticals was compared. Results When adopting manual dispensing, the numbers of 1-10 μm insoluble particulates in different groups in class Ⅰ environment were less than those in class Ⅲ environment respectively, differences were all statistically significant (all P<0.05). When adopting a new mode of dispensing in relatively closed environment, there was no significant difference in the numbers of 1-15 μm insoluble particulates in different groups between class Ⅰ and class Ⅲ environment respectively (all P>0.05). The numbers of 1-20 μm and 1-15 μm insoluble particles in different groups were less than those in manual dispensing when the new mode of dispensing were adopted in class Ⅲ and class Ⅰenvironment respectively, differences were all statistically significant (all P<0.05). The numbers of 1-15 μm insoluble particles in different groups in manual dispensing in class Ⅰ environment were more than those in class Ⅲ environment respectively, difference were all statistically significant (all P<0.05). Conclusion The relatively closed environment dispensing mode can effectively reduce environmental particulates entering intravenous infusion system during dispensing process.