Abstract: The study was conducted to evaluate the effects of probiotic supplementation (Bacillus subtilis) in diet on performance, blood properties and microflora of Shaoxing duck. A population of 200 laying ducks (160 days old) was divided into two groups each having five replications. The control (T0) were fed on basal diet while T1 with Bacillus subtilis 1 x 108 CFU/kg in addition to basal diet for thirty five days. The results showed that for T1 group, the egg laying rate increased (3.79%) significantly, while a decrease of about 12.60%, 23.52% and 40.14% was observed in egg triglyceride, total cholesterol and malondialdehyde, respectively. However, the blood glucose content and alkaline phosphatase activity increased by 15.13% and 53.41%, significantly. Moreover, there was a decrease of blood cholesterol, uric acid and ammonia in T1 by 28.86%, 22.39% and 62.5%, respectively. As compared to T0, T1 showed a significant increased in the amount of caecal microflora, i.e. general aerobic bacteria (18.68%) and Lactobacillus (9.92%). In conclusion, supplementation of Bacillus subtilis in diets had significant effects on some aspects of egg composition, biochemical properties of blood and few microflora of Shaoxing ducks.