Siliceous　mesocellular　foam　(MCF)　was　employed　as　carriers　in　the　immobilization　of　papain,　and　the　properties　and　the　stabilities　of　the　immobilized　enzyme　were　investigated　in　detail.　The　results　show　that　the　amount　of　papain　immobilized　on　MCF　material　reaches　334　mg/g　MCF.　The　optimal　pH　and　reaction　temperature　of　the　immobilized　papain　are　7.5　and　50　degrees　C,　respectively.　The　Michaelis　constant　(Km)　of　immobilized　papain　is　disclosed　as　6.99　x　10(-3)mol/L　by　the　Lineweaver-Burk　plot　at　37　degrees　C.　The　immobilized　papain　with　65.1%　of　the　activity　remaines　after　repeating　the　catalysis　of　casein　for　8　times.　After　stored　at　4　degrees　C　for　60d,　the　immobilized　papain　retaines　75%　of　the　activity,　while　the　free　papain　only　retains　53.6%.　The　pH,　thermal,　operational,　storage　stabilities　of　the　immobilized　enzyme　are　improved　due　to　the　large　pore　microenvironment　and　the　shield　of　the　mesopores　of　MCF,　which　can　be　considered　as　excellent　supports　for　papain　immobilization.