DGCI, Hv, I2, I3, (2G-R-B)/L* and Hv*Diff, which are the color index of leaves, were acquired by using computer vision technology. Combining those indexes with BP network, multiple regression models and genetic algorithms, the predictive model for chlorophyll relative content was established The value of SPAD for leaves is simulated by mathematics, and the mathematical expressions of model is Y=purelin[W5* tansig(W4* X, B4), B5]. Using the established model to predict the value of SPAD, relative error rate is 3.355 7 % between the results and measured data in field.