There are about 2,000,000 tons of rice straws produced per year in Taiwan. Rice straw could be used as moisture content control material for agricultural organic compost, and by doing this, it will become one of the models for recycling usage of wastes. This study applied a crusher on rice straw to test the various treatments on rice straw before composting, for instance, the length of rice straw, the gap of crusher, the crushing speed, and the replication of crushing. The index for these treatments was moisture content of rice straw. The quality of compost of rice straw mixed with cow’s, pig’s and chicken’s manure was also analyzed to explore the feasibility of rice straw composting. Results showed that the highest moisture content was achieved in 7 cm long rice straw compressed at 300 rpm and 0.5 mm gap after 180 min water absorption. The rice straw that were crushed three or four times and mixed with animal manure in 1:1.5 ratio, could achieve 77 °C in temperature. The composting day could also be reduced about 29% compared to no crushed rice straw mixed with animal manure. After fermentation, the physical and chemical analyses indicated that the product of rice straw compost contented 32—35% in moisture content, 7.3 in pH, 11-12 in C/N ratio, 56~41% in organics, 2.91—3.05% in N content, 2.92~3.01% in P content, 1.65% in K content, 32~35% in total C. These compositions met the requirement of animal compost standard in Taiwan. During the fermentation, the CO2 and NH3 content also met the related regulation. Thus the process for rice straw composting suggested by this study is a feasible and fast method.