The target microbial community in different phases of green waste (GW) composting and lignocellulose transformation mechanism were studied in GW composting by using MiSeq sequencing and PICRUSt tools. The results showed that the composting process could be divided into four phases. In each phase the temperature, microbial genera, substrate and product were different. Each phase of the composting appeared in turn and was unable to jump. Humic acid (HA) and fulvic acid (FA) can regulate the composting process and lignocellulose degradation in the process of composting material transformation. The calefactive phase and the cooling phase are the incubation phase of mesophilic microorganisms. In the calefactive phase, microorganisms decompose small molecular organics such as FA for growth and reproduction; while in the cooling phase, microorganisms degrade HA and FA for growth and reproduction. In the early stage of the thermophilic phase, thermophilic microorganisms decompose HA for growth and reproduction, while in the later stage of the thermophilic phase, microorganisms decompose lignocellulose to produce HA and FA. In the maturation phase, microorganisms synthesize humus using FA, amino acids and lignin nuclei as precursors. In the four phases of the composting, different representative genera of bacteria and fungi were detected. Among which, one bacterial genera, Streptomyces, and two fungal genera, Myceliophthora and Aspergillus, maintained high abundance in all phases of the compost. Correlation analysis showed that some non-filamentous bacteria, actinomycetes and fungi were significantly correlated, indicating that bacteria, actinomycetes and fungi had synergistic effect on the degradation of lignocellulose.