Abstract: To discover novel fluoroquinolone lead compounds as possible anti-infective or/and antitumor chemotherapies, combination principle of pharmacophore-based drug design, a series of novel tricyclic fluoro­quinolone title compounds, 1,2,4triazino3,4-h1,8naphthyridine-8-one-7-carboxylic acid derivatives (5a-5p), were designed and synthesized with a fused 1,2,4-triazine ring unit. Their structures were characterized by spectral data and elemental analysis and the in vitro antibacterial and anti-cell proliferation activities were also evaluated. The results showed that the titled compounds exhibited more significant inhibitory activities against drug-resistant bacteria (Methicillin-resistant Staphylococcus aureus and multi drug-resistant Escherichia coli strains) and three tested cancer cell lines (human hepatoma SMMC-7721, murine leukemia L1210 and human murine leukemia HL60 cells). Interestingly, SAR showed that compounds with electron-donating groups attached to benzene ring had stronger antibacterial activity than antitumor activity, but electron-withdrawing compounds displayed more potential antitumor activity than antibacterial activity, especially antitumor activity of nitro compounds was comparable to comparison doxorubicin. Thus, novel triazine-fused tricyclic fluoroqui­nolones as potent anti-infective or/and antitumor lead compounds are valuable to pay attention and for further development.