Abstract: OBJECTIVE To observe the bacterial colony counts at different time points of use of lubricant solution and the impact on the quality of cleaning of surgical instruments so as to strengthen the control of quality of the surgical instruments and ensure the medical safety. METHODS A total of 180 surgical instruments that were collected in May 2015 were randomly divided into 6 groups, with 30 instruments in each group. The surgical instruments were treated with flushing, multienzyme cleaning, and terminal rinsing, then the surgical instruments were respectively soaked in the lubricant solution for 4, 8, 10, 12, and 24 hours after they were tested qualified by the visual inspection and ATP bioluminescence assay.The bacterial colony counts in the lubricant solution and the quality of cleaning of instruments were monitored at the different time points. RESULTS The bacterial colony counts in the lubricant solution were increased with the time of application. The ATP bioluminescence assay and bacterial colony counting were carried out for the lubricated instruments, all of which were qualified after they were soaked in the solution for 4, 8, and 10 hours. The ATP bioluminescence assay showed that 4 instruments were unqualified after they were soaked in the solution for 12 hours and that 11 instruments were unqualified after they were soaked in the solution for 24 hours; the unqualified rates were 13.33% and 36.67%, respectively. The bacterial culture of the lubricant solution showed that 3 and 12 instruments were respectively unqualified, and the unqualified rates were 10.00% and 40.00%, significantly higher than those of the instruments that were soaked in the solution for 4, 8, and 10 hours (P<0.05). CONCLUSION The bacterial colony counts in the lubricant solution are increased with the time of use, and the use of lubricant solution for more than 10 hours may influence the quality of cleaning of the instruments.