Objective To observe the best dressing change frequency of Shengji Ointment in order to treat chronic ulcer and discuss the possible mechanism. Methods After being made into the ulcer models

30 New Zealand white rabbits were divided into 1-day group

2-day group and 3-day group

with 10 in each group. The 1-day group

2-day group and 3-day group changed the dressing daily

every 2 days and every 3 days respectively

for 6 days. The secretion weight

as well as content of interleukin-1β（ IL-1β） and transforming growth factor-β1（ TGF-β1） in ulcer secretion were measured

and the healing time was recorded. Results The weight of secretion for all 6 days

weight of secretion per unit area on day 6 and the IL-1β levels in the 1-day group were the highest

while on day 6

the TGF-β1 levels in the 2-day group achieved the highest

and there were significant differences in the results between every two groups（ P < 0. 05）. As for healing time

the 2-day group had the best results among the groups（ P < 0. 05）. Conclusion The best dressing change frequency of Shengji Ointment was every 2 days

and its possible mechanism could be related with the increase of TGF-β1 in secretion.