A　compressed　domain　speech　enhancement　method　based　on　the　joint　modification　of　adaptive　and　algebraic　codebook　gains　for　the　codec　of　ITU-T　G.722.2　is　proposed　in　this　paper.　First　the　power　of　excitation　signal　corresponding　to　the　noise　is　estimated　by　the　method　of　minimum　statistics.　Then　the　decision-directed　approach　is　used　to　get　an　estimate　of　the　a　priori　SNR.　And　the　algebraic　codebook　gain　is　modified　by　multiplying　a　Wiener-type　modification　factor.　In　order　to　solve　the　problem　of　power　loss　in　voiced　segment,　the　modified　adaptive　codebook　gain　is　got　by　keeping　the　power　of　the　modified　excitation　signal　equal　to　the　scaled　version　of　the　noisy　one.　The　result　of　performance　evaluation　under　ITU-T　G.160　shows　that,　in　comparison　with　the　method　that　only　modifies　the　algebraic　codebook　gain,　the　proposed　method　could　provide　larger　amount　of　noise　reduction　in　both　white　and　colored　noise　with　smaller　attenuation　on　the　speech　level,　and　the　objective　speech　quality　is　improved　evidently.