The unfolding processes of two hemoproteins including hemoglobin（Hb） and cytochrome c（Cyt c） were investigated by using UV-Vis absorption and fluorescence emission spectrometry.The unfolding behaviors of Hb and Cyt c were induced with two chemical denaturing agents of guanidine hydrochloride（GdHCl） and urea.Weak bonding energy between heme groups and the histidine on Hb peptide caused the poor stability of heme groups and their easier dissociation from the peptide of Hb only in 3.0 mol/L GdHCl.However,high bonding force due to the disulfide bond between heme group and cysteines on Cyt c peptide chain increased the stability of Cyt c.Heme group did not dissociate from Cyt c peptide with high concentration of 6.0 mol/L GdHCl.The research provides an important basis for the elaboration of relationship between protein functions and their conformations.