Poly-beta-hydroxyl butyrate (PHB) is a biodegradable thermoplastic which can be extracted from a wide range of bacteria as intracellular granules. They are used in packaging, medicine and agriculture for a wide range of applications. The aim of the present work was selection of Bacillus subtilis PHB producers. In this study, the Bacillus subtilis from soil were isolated and identified, and their PHB production was determined under different conditions such as incubation time, carbon source and nitrogen source. The results showed that, starch was the best carbon sources with significant effect and was better in PHB production and known as low cost substrates to compare with the other sources .Amongest variety of nitrogen sources, glycine was the most suitable. At last, the best optimum incubation period and starch concentration to PHB production were 48 hours and 5% (v/v) and for glycine were 48 hours and 3% (v/v) respectively. The results showed that the best percent of carbon source in PHB production, was not the highest amount, but the best concentration was that do not lead to limitation of bacteria growth.