A series of new 2-(1-(2-(substituted-phenyl)-5-methyloxazol-4-yl)-3-(2-substitued-phenyl)-4,5-dihydro-1H-pyrazol-5-yl)-7-substitued-1,2,3,4-tetrahydroisoquinoline derivatives were synthesized. The results showed that compounds 9q and 10q can strongly inhibit Staphylococcus aureus DNA gyrase and Bacillus subtilis DNA gyrase (with IC(50s) of 0.125 and 0.25 microg/mL against S. aureus DNA gyrase, 0.25 and 0.125 microg/mL against B. subtilis DNA gyrase). On the basis of the biological results, structure-activity relationships were also discussed.