Objective To study the protein conformational change of placenta tissue by using Raman spectrum.Methods By using Raman spectroanalysis,we detected the placenta protein conformational change of GDM and control groups.Results(1)In the placenta of GDM,the absorption bands of tryptophan and phenylalanine were increased obviously.(2)In the placenta of GDM,the secondary structure of protein was composed of α-helix,random coil and β-sheet.Conclusions In the placenta of GDM,the orderly conformations of main chains in protein are decreased.Side chains of amino acids,especially tryptophan and phenyl-alanine,are changed greatly.The structure variation of protein may be correlated to the diabetic complications.