ObjectiveTo compare the disinfection efficacy of different disinfectants on dental unit waterlines (DUWLs). Methods18 sets of DUWLs were randomly divided into 4 groups, and disinfected or treated with  hydrogen peroxide (H2O2) disinfectant, sodium hypochlorite  (NaClO) disinfectant, hydrogen peroxide silver ion disinfectant(Sanosil),and  distilled water (DW) respectively. Water specimens from triple syringes and highspeed handpieces were taken, bacterial count before and after disinfection were compared. ResultsBefore disinfection,no significant differences in bacterial counts were found among four groups (all P>0.05), bacterial counts of DUWLs of all groups severely exceeded the standard(all＞3 000 CFU/mL）. After disinfection,except DW group, bacterial counts of DUWLs of the other groups declined dramatically  (all ＜100 CFU/mL）, bacterial count after disinfection were all obviously lower than  before disinfection （all P＜0.001).One week after disinfection, bacterial counts among three disinfectant groups in different time periods were statistically different (triple syringes: Day1—Day5,all P<0.05; highspeed handpieces:  Day2,Day3 and Day5，all P＜0.05). Day3 after disinfection of triple syringes by H2O2 and  NaClO, Day4 after disinfection of highspeed handpieces by H2O2 and  NaClO, and Day5 of triple syringes and highspeed handpieces by Sanosil all exceeded the standard of  Center for Disease Control and Prevention of America. One week after disinfection, bacterial counts of three disinfection groups all exceeded or approximated to that before disinfection. ConclusionThree types of disinfectants can all effectively reduce bacterial load in DUWLs. Compared with  other disinfectants, Sanosil has advantage of inhibiting bacterial growth after disinfection.