In this study, a fixed-bed biofilm reactor using hybrid zeolite and plastic bio-carriers was constructed, in which successful enrichment of glycogen accumulating organisms (GAOs) under oscillating filling (anaerobic) - draining (aerobic) conditions was achieved. Associated with zeolite chemical adsorption, anaerobic removal of COD by GAOs and ammonia by zeolite was achieved. The hybrid carrier bioreactor was fed with synthetic wastewater with COD and ammonia concentration of (508±19)mg/L and (40±3)mg/L, respectively, and operated under periodical cycles of anaerobic (6 h) and aerobic (6 h). The removal rates of COD, ammonia nitrogen, and total nitrogen (TN) by single-stage treatment were 89.2%, 57.5%, and 57.5%, respectively. The removal rates of COD, ammonia nitrogen, and TN by the two-stage reactors were 93.1%, 84.9%, and 70.8%, respectively. By reducing the HRT by 50% (anaerobic/anoxic 3 h + aerobic 3 h), the TN removal rate in the two-stage reactors was increased to 81.7%. The results of 16S rRNA high-throughput sequencing showed that the relative abundance of Candidatus Competibacter (GAOs) increased by 30.43 times (0.46% → 14%) on the surface of the plastic carrier, while it only increased by 14.35 times ( 0.46%→6.60%) for the zeolite carrier, indicating that the surface of the plastic carrier is more favorable for the enrichment of Candidatus Competibacter.