Abstract: Amino acid is of virtual significance to investigate t he diffusion behavior of amino acid in aqueous solution.Real-time holographic i nterferometer is employed to study the diffusion of glycine,alanine,valine aci d at 298.15K,and diffusion coefficients under 5 various concentrations are meas ured respectively.In addition,the experimental results and affecting factors a re analyzed and discussed.This investigation provides a fundament to profoundly study the diffusion and mass transfer mechanism of amino acid in aqueous soluti on.