The　sulfomethylated　lignoamine　was　prepared　with　masson　pine　lignosulphate　by　Mannich　reaction　and　sulfonation　reaction.　Then　the　organic-inorganic　compound　modified　lignin-based　flocculant　could　be　obtained　by　further　mixing　with　sodium　aluminate　solution.　The　modified　lignin-based　flocculant　was　adopted　to　treat　the　antibiotics　pharmaceutical　effluent.　The　flocculation　conditions　were　optimized.　The　removal　rates　of　CODCr,　SS　and　colourity　of　the　effluent　could　reach　61.2%,　96.7%　and　91.6%　respectively　under　such　conditions　as　effluent　pH　value　6.0　and　flocculant　dosage　120　mg/L　etc.　Moreover,　the　comparison　tests　with　various　flocculants　indicated　that　the　flocculation　performance　of　the　modified　lignin-based　flocculant　apparently　prevailed　over　such　flocculants　as　polyacrylamide　(PAM),　polyferric　sulfate　(PFS),　potassium　aluminium　sulfate　(PAS)　and　ferrous　sulfate　(FS)　etc.