Abstract: The composition ratio of amylose and amylopectin in rubberwood directly affects the chemical properties of starch. During the thermally modified process of rubberwood, the thermal degradation of starch affect the change of composition ratio of amylose and amylopectin. In this study, the extraction parameters of starch from rubberwood was optimized by using single factor method, and the quantitative analysis of amylose and amylopectin in rubberwood samples was carried out by double-wavelength spectrophotometry, whose precision, stability and recovery rate were tested. The results showed that the regression equation of standard curves of amylose and amylopectin were y=0.02499x−0.1136 and y=0.00159x−0.0005, respectively, with regression coefficients R² of 0.998. The pretreatment method of samples was simple and rapid, and the analytical method had good stability, high sensitivity and stable recovery. Thus, it is suitable for the quantitative analysis of amylose and amylopectin in rubberwood. The contents of amylose and amylopectin in untreated rubberwood and thermally modified rubberwood at different temperatures (125, 155, 185 ℃) were analyzed. The content of amylopectin in rubberwood is much higher than that of amylose, and the ratio was about 8∶1. With the thermal modification temperature increased to 155 ℃, the amylose content decreased significantly, while the amylopectin content decreased sharply with the temperature increased to 185 ℃.