1-(2-fluorophenyl) piperazine and 1-(4-fluorophenyl) piperazine were used to interact with bromoacetic acid respectively to form derivatives which were again used to interact with 4-hydroxycoumarin to synthesize piperazine coumarin derivatives A and B, whose antibacterial activities were then studied. The minimum bacteriostastic concentrations of A and B against Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Pseudomonas aeruginosa were determined through double dilution method. The results showed that both A and B had good bacteriostastic effects on the four bacterial strains tested, among which B was superior to A and produced the best bacteriostasis effect on Bacillus subtilis, and its minimum bacteriostastic concentration was 0.337 ug/mL, which was better than that of the positive control chloramphenicol.