Abstract: This study aimed to explore effect of microorganisms and different carbon-to-nitrogen（C/N）ratios on compost maturation efficiency of fruited mulberry branches for a large compost pile（500 kg）.Fruited mulberry branches and chicken manure were used as C and N sources，respectively，for the compost pile，and the C/N ratios were adjusted to 20∶1，25∶1，and 30∶1.Subsequently，4%，4%，and 6% of microorganisms were stirred into the piles.During composting process，temperature was maintained above 45 ℃ for 15 d to effectively degrade the refractory organic substances.Consequently，effects of microorganisms and C/N ratios on the compost maturation efficiency and fertility of mulberry branches were determined.Results showed that the highest maturation efficiency and the best effect under Pile No.1，inoculated with 6% of microorganisms and with a C/N ratio of 30∶1.After composting，its C/N ratio decreased to 11.73∶1.Soluble humus and total nutrients had the greatest increase，and accumulation of their contents was the highest.Germination index reached 133.91%，and the T value was 0.39.C/N ratio was an important factor affecting compost maturation efficiency of mulberry branches.A proper C/N ratio optimizes decomposition by microorganisms and improves fertility of compost.In addition，increasing quantity of inoculated microorganisms can improve compost maturation efficiency.