OBJECTIVE： To study the influence of oscillator on the cleanliness of class 100 clean bench in PIVAS. METHODS： Using sedimentated bacteria and the number of dust particle as index， in common drug configuration room， antibiotics configuration room and risk drugs configuration room including biological safety cabinet and horizontal laminar flow， the cleanliness of class 100 clean bench were monitored when oscillator was set at clean bench and different positions in work and non-working state. RESULTS & CONCLUSIONS： In working and non-working state of oscillator， there was no difference in sedimentated bacteria and the number of dust particle which was in line with the requirements of 2010 edition of GMP， i.e. the application and location of oscillator didn’t influence the cleanliness of class 100 clean bench. From a view of safety， it is suggested to place the oscillator in the left （or right） posterior wall of clean table when biological safety cabinets is used to dispense antibiotic and risk drugs.