This study was carried out to investigate the effect of storage time on the color and chemical compounds of bagasse particleboard made. For this purpose, the three levels of stored and fresh bagasse from karoon particleboard Company were used. In addition, the chemical compositions were determined according to the TAPPI test methods and also biometrical (slenderness ratio) was done using the fiber dimension measured by Franklin method. The results showed that the amount of lignin was different in the stored samples at three levels, but the difference in the amount of cellulose and extractive was not observed. The results illustrated that the color changes in the stored bagasse were more than fresh sample. Identification of the microorganisms in stored samples was done and results showed that most of microorganisms were bacteria and yeast. The results showed that the storage time can significantly effect the color and physical properties of stored bagasse