Abstract: The correlation between the rice leaf chlorophyll content and leaf spectral absorption variables are studied in a area experiment．Results show that shooting stage, heading stage and milking stage are sensitive stages for diagnosis of the leaf chlorophyll content in rice. The spectral variables formed by the best sensitive wave band infer rice leaf chlorophyll contents. In the heading stage and milking stage, the inferring ability of logarithm adding obviously surpasses that of SPAD value. The inferring ability of SPAD value just slightly surpasses the logarithm-sum model in the shooting stage. The explanation can survey the chlorophyll value accurately with each period of duration corresponding sensitive spectral wave band. This article proposes some exploring research for enhancing survey performance of SPAD-520.