Three series of novel oxo-heterocyclic fused naphthalimide derivatives (8a–8f, 13a–13d, 17a–17d) were prepared. The newly-synthesized compounds, and their thio-heterocyclic fused analogs (1a–1c, 2a–2d, 3a–3c) exhibited potent antiproliferative activity correlated well with their structure. Further research demonstrated that all the representative compounds 13a, 2a and 17a, 3a showed strong inhibition