The polyhydroxyalkanoate (PHA) accumulation ability of raw Conventional activated sludge (CAS) can be improved with proper acclimating method, which is necessary for high PHA yield. This study compared two acclimating strategies: onestep acclimation and twostep acclimation. The comparison was based on the PHA production activity, substrate utilization rate and sludge characteristics. The onestep acclimation performed a PHA yield of 019 g／g acetate acid and an acetate acid utilization rate of 88 mg／(L·min). The PHA maximum content was obtained 90 min later after substrate feeding accomplished. The final biomass concentration (MLVSS) was around 2 000 mg／L. The data of these three criteria for the twostep acclimation were 024 g／g acetate acid, 273 mg／(L·min), 30 min and 4 500 mg／L, respectively,which were all increased. Our study indicated that the twostep acclimating strategy was more suitable to cultivate PHAproduction CAS.