Composting has recently become popular as a means of recycling swine manure into products for sale off the farm, but bulking agent(usually sawdust) are expensive and availability is limited. This experiment was conducted to investigate the effect of fly ash as a bulking agent on the composting of swine manure and to analyze the effective substitution rate of fly ash mixed with swine manure for sawdust. Fly ash was able to be substituted for sawdust and the most effective substitution rate are 50% of sawdust. According to the results the advanced research and development are required, the effect of swine manure with fly ash on the soil properties, forage composition and animal performance.