Abstract: The relationships among moisture content, maturity and grinding degree of the compost were studied with chicken manure and straws as raw materials. The results show that water content is the first factor in controlling grinding degree. Grinding degree is decreased with moisture content increasing, which satisfies two-order kinetics equation. The critical water content is about 20% for grinding well. Maturity has great effect on grinding degree when water content is more than 20%. With the composting time going on, mature compost is easy for grinding. There is no significant correlation between the grinding degree and some maturity parameters including GI, EC and pH value. However there is significant relationship between the grinding degree and TOC, TN and C/N value. There is significant linear correlation between the grinding degree and chemical parameters of compost including hemicellulose and cellulose, while there is no significant correlation with lignin.