16-isopropyl-5, 9-dimethyltetracyclo [10.2.2.0(1, 10).0(4, 9)] hexadec-15-ene-5, 14-dicarboxylic acid (1b) was prepared from rosin through a Diels-Alder addition reaction. Then, a group of Schiff bases derived from 1b was synthesised. Their structures were characterised by IR,(1)H-NMR, MS and elemental analysis. The antibacterial activities of these newly synthesised Schiff bases were also investigated. The results show that these compounds possess antibacterial activities against Staphylococcus aureus and Escherichia coli. Among them, compounds 5a, 5b and 5c, exhibit remarkable antibacterial activity against E. coli.