An experiment was conducted to evaluate the effects of dietary supplementation of beta-glucan (Glu) at different levels in the diets on the performances, feed conversion ratio and servival proportion of commercial Cobb broiler chickens. Total 320 Cobb500 chickens at 1 day of age were divided into 4 groups of 4 treatments. The control (Glu0) was basal diet without any beta-glucan supplementation in the diet, other treatments were Glu0.3 (0.3g/kg feed), Glu0.6 (0.6g/kg feed) and Glu0.9 (0.9g/kg feed). Average daily gain (ADG) from birds fed with 3 supplemented level diets with Glu0.6 (60,2 g/day), Glu0.9  (60.6 g/day ) were higher than that from Glu0.3 (57.8 g/day) and control (57.0 g/day). Feed intake was non significant differences between 4 treatments. Howevers, there were slightly lower feed conversion ratio (FCR) in Glu0.6 (1.75 g feed/g gain) and Glu0.9 (1.73 g feed/g gain) compared with Glu0.3 (1.88 g feed/g gain) and control (1.85 g feed/g gain). Moreover, E.coli content in the chickens feces was highest in the chickens fed control (1.79 x10⁶ CFU/g  feces) and lowest in Glu0.6 (1.73 x 10⁶CFU/g feces). The morbility and mortality of chickens fed Glu0.6 was lowest (15.0% and 3.75%) in comparision with control diet (31.3% and 12.8%). In conclusion, it should be better in growing performance of broiler Cobb chickens when suplementation of beta-glucan at 0.6 g/kg feed to diet insteat of using antibiotic in commercial broiler diet.