In order to study biochemical parameters of maize leaf, which infected by maize southern rust, Fourier transform infrared spectroscopy was applied to obtain the spectra of infection and normal maize leaves. The characteristic region and fingerprint region at spectrum were selected to study the change of protein and carbohydrate in maize leaf. Compared infection with normal leaf spectrum, amide bands had diversification obviously, the change of absorption band of carbohydrate was not prominence. It showed that the protein secondary structures had changed, and the diversification of carbohydrate in infection leaf was not obviously. Curve-fitting analysis of wave number at 1 800~1 480 presented the sheet and helix in protein secondary structures was decrease in infected leaf, and the turn structure was increase at the infected initial stage. The random coil structure was increase rapidly at infected end stage, this structure was absent at infected initial stage and normal maize leaves. The results show that Fourier transform infrared spectroscopy combine with curve-fitting analysis can be used to explore the change of biochemical parameters in infection maize leaf, which provides evidence for studying the disease resistance of maize.