The present study was done to investigate the effect of dietary supplemental freezer dry powder fermentation soybean by Bacillus subtilis (natto) on the growth performance and intestinal microflora, prevention of fowl typhoid infection, the uptake of vegetative diet in broiler chickens. The chickens were fed control diet (supplement antibiotics) and fermentation soybean (0.75, 1.5, 3%) diets. A total of 280 one day old broiler chickens with randomly mixed sexes were fed the four diets for 6 weeks. Body weight gain of chicken fed 1.5% fermentation soybean by B subtilis tend to increase higher than the control from 6th week. Chickens fed diets containing 1.5% fermentation soybean by B subtilis had higher intake than those fed the other levels to the 3th weeks, but lower than control from the 4th week to the 6th week. Feed conversion also improved significantly in the supplemental 1.5% fermentation soybean by B subtilis from the 4th week to the 6th week. The number of B subtilis and Lactobacillus spp in the ileum and cecum tend to increase in the supplemental fermentation soybean by B subtilis at 6 week of age, but was not significantly different. In the nutrient digestibility, the feed conversion on the supplemental 1.5% fermentation soybean by B subtilis was better than the control and the weight of drying feces lower than the control. In test of S. gallinarum intramuscular inoculation, reisolation rate of S gallinarum in liver and feces 1.5% the fermentation soybean by B subtilis 75% (liver), 17% (feces) had decreased than the control.