The optimization of poly-S-hydroxybutyrate (PHB) fermentation process is essential to obtain a high PHB productivity. An optimization of two-stage continuous, culture system by complex method for PHB production is presented. PHB production rate off the system obtained in the present study was chosen as the objective function. The PHB production rate of the system was higher than that of the phasewise optimization method which maximises the growth rate of residual biomasa in the first stase and the IIl prmluccion rate in the second satge. When the inlet glucose concentratiun in the first satae increased, PHB content and yield also increased. When the fermenter volume ratio (V₂/V₁) was 0.5, maxinntm IIB productivity in the second stage was 2.86 g/L·h, which is highest compared with the reported value on YEIK.