ObjectiveTo realize the contamination status of dental unit waterlines (DUWL) in general hospitals,  and provide scientific evidence for  making preventive measures. MethodsThree hospitals were selected for study, water source adopted by hospital A,B and C was running water, reservoir water, and filtered water through reverse osmosis filtration system respectively, specimens of dental handpiece spray water and flushing water of dental chair units were collected quarterly, total bacterial colony in water were detected.  ResultsThe qualified rate of source water, handpiece spray water, and flushing water  in hospital  A was 75.00%（3/4）, 0 (0/40)  and 0 (0/40) respectively,  colony count of handpiece spray water and flushing water was （1.20×103-5.53×104 ）CFU/mL（M=3.80×104 CFU/mL） and （2.11×104-1.66×105）CFU/mL（M=4.80×104 CFU/mL）respectively.The qualified rate of source water, handpiece spray water, and flushing water in hospital B  was 50.00%(2/4), 60.00%（24/40）and 72.50%(29/40) respectively, colony count of handpiece spray water and flushing water was  （0.00-3.71×106）CFU/mL（M=83.00 CFU/mL） and （0.00-2.39×106 ）CFU/mL（M=72.00 CFU/mL）respectively.The qualified rate of source water, handpiece spray water, and flushing water in hospital C  was 100.00%(4/4), 55.00%（22/40）and 65.00%（26/40）respectively, colony count of handpiece spray water and flushing water was （0.00-6.20×103） CFU/mL（M=96.00 CFU/mL） and（0.00-1.63×103 ）CFU/mL（M=87.50 CFU/mL）respectively. ConclusionWater of DUWL in general hospitals is seriously contaminated， disinfection and standardized management of source water and DUWL must be strengthened.