Abstract: A method for recovering PHB(poly- -hydroxybutryate)from recombinant E.coli by using surfactant SDS(sodium-dodecyl sulphate) was studied.The factors,including reaction time, temperature,concentration of SDS and pH were optimized.The results showed that temperature had no effect on the purity of PHB,while SDS treated biomass for more than 10 minutes at a higher pH or concentration of SDS could result in higher PHB with lower molecular weight.At 20℃ and pH12,when 3g·L~(-1) SDS was used to treat 30g·L~(-1) cells for l0 minutes,83.05% proteins in the cells could be removed,whereas the purity of PHB was increased from 71.86% to 95.18% and the molecular weight of PHB was 983000(the initial molecular weight was 1180000).