To clarify the effect of propionate concentration on propionate degradation, propionate degradation feature at different propionate concentration conditions was investigated. A mesophilic syntrophic propionate-oxidizing bacterial community (containing propionate-oxidizing bacteria and methanogens) was firstly obtained by 15 times subculture using propionate as sole carbon source. Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) revealed that the main propionate-oxidizing bacteria belonged to genus Syntrophobacter while hydrogenotrophic methanogens and aceticlastic methanogens were related to Methanobacterium and Methanosaeta, respectively. Then the batch test was performed for evaluating the effect of propionate concentration on syntrophic propionate degradation. The results showed that the propionate was rapidly degraded at propionate concentration of 1 000-2 000 mg／L under the inoculated sludge of 0.81 g／L condition. However, the propionate degradation was inhabited when the propionate concentration was 2 500-3 000 mg／L. The inhibition was gradually relieved with extension of time. It implied that high concentration propionate (≥2 500 mg／L) would inhibit the metabolic activity of propionate-oxidizing bacteria and this inhibition was reversible.