Abstract: To elucidate the microbial compositional shifts and spoilage-related microorganism succession in grass carp (Ctenopharyngodon idella) meat during refrigeration, metagenomic sequencing was employed to analyze microbial profiles at fresh (D0, D3), transitional (D6, D9), and spoiled (D15) stages. Results indicated a significant correlation between microbial community succession in grass carp meat and refrigeration duration, with microbial diversity initially increasing and then decreasing over storage time. Notably, the transitional phase (D6) emerged as the pivotal factor driving substantial divergence in microbial composition. At the phylum level, Actinobacteria (69%) and Proteobacteria (20%) dominated during the initial 3 day refrigeration. A marked structural shift occurred by day 6, with Proteobacteria (51.77%) and Firmicutes (11.76%) becoming predominant. By day 9, Proteobacteria exhibited a substantial increase, ultimately exceeding 98% relative abundance at the spoiled stage (D15), establishing itself as the primary phylum driving spoilage. Genus-level analysis revealed dynamic compositional changes: The dominant genera transitioned from Kocuria (fresh stage, D0~D3) to Pseudomonas, Achromobacter, Acinetobacter, and Psychrobacter (transitional stage, D6~D9), with Pseudomonas ultimately prevailing in the spoiled phase (D15). Principal coordinates analysis (PCoA) indicated high structural similarity among fresh-stage samples (D0, D3), whereas later stages (D6~D15) exhibited significant divergence (P<0.05), displaying dispersed clustering in ordination space. T-test analysis identified 10 genera with statistically significant (P<0.05) abundance variations during refrigeration: Enhydrobacter, Macrococcus, Brevibacterium, Kocuria, Corynebacterium, Dermacoccus, Psychrobacter, Pseudomonas, Achromobacter, and Brochothrix. The ecological network analysis elucidated the microbial community succession from environmental bacteria to psychrophilic bacteria and ultimately to spoilage bacteria, while identifying stage-specific indicator microorganisms (Aeromonas (D0), Macrococcus (D3), and Psychrobacter (D9)). Furthermore, it demonstrated the topological evolution of microbial networks through successive phases of symbiosis (D0, D3), competition (D6), and spoilage dominance (D15). These findings on microbial diversity and structural evolution provide critical insights for monitoring quality assurance and developing targeted preservation strategies in refrigerated grass carp products.