In the present study, temporal dynamics of shearing force of rice stem was investigated. Results showed that shearing force was significantly greater at lower moisture content. Shearing force of stem increased with advancing maturity stage. Cellulose and hemicellulose content of stem increased over time. On the same sampling date, shearing force decreased from lower part to upper part of the plant. There was positive relationship between shearing force and cellulose content, and between shearing force and hemicellulose content, but there was no relationship between shearing force and lignin content. It is suggested that the energy requirement for precutting rice straw will be significantly less if rice is harvested earlier than the traditional harvest date without prejudicing grain yield. In the meantime, the rice straw will have higher nutritive value as animal feed. These data are also useful for the design of rice harvesting machine or rice straw precutting equipment.