Succession and metabolism functions of bacterial communities were determined in maize straw composting with earthworm casts and zeolite addition by using high-throughput sequencing, Biolog and PICRUSt. Results showed that earthworm casts and zeolite addition increased the temperature, decreased NH4+ contents and affected bacterial community structure. The relative abundances of Firmicutes and Betaproteobacteria increased with earthworm casts and zeolite addition in the late stage. The abundances of genes related to carbohydrate metabolism, amino acid metabolism, and energy metabolism were increased by these two additives in the early stage, but decreased in the late stage. Network analysis demonstrated that members of Bacillaceae were identified as the keystone taxa. Temperature showed negative relationship with Georgenia, while NH4+ exhibited positive associations with Georgenia, Devosia, Ruania and Mycobacterium. These results indicated that earthworm casts and zeolite addition benefitted the keystone species and enhanced the metabolism capacity of bacterial community, thereby improved the quality of compost.