Abstract: Seventeen derivatives of 7-(4,7-di-substituted conmarin-3-acetamido)cephalosporins were synthesized with acid chloride method, Vilsmeier reagent method and mixed anhydride method. Isolation and purification were fulfilled with Sephadex LH-20 column chromatography and centrifugal-TLC technique. Their chemical structures were identified by elemental analysis, IR and ~1HNMR spectrum. The preliminary antibacterial activity tests showed that these cephalosporin derivatiyes exhibited good activity against Gram-positive bacteria and individual Gramnegative bacteria. Further experiments in pharmacology will be made.