Abstract: Based on coumarin core structure as the procaspase-3 activator 1541 from our previous study, twelve coumarin derivatives bearing benzothiazole or benzene moiety were designed and synthesized. Target compounds were evaluated for in vitro antitumor activity against a procaspase-3 overexpressing cancer cell line (human histiocytic lymphoma cell, U937) and a procaspase-3 no-expression cancer cell line (human breast adenocarcinoma cell, MCF-7) to rule out off-target effects. The results revealed that coumarin derivatives bearing benzothiazole showed more potent inhibition activity and selectivity against procaspase-3 over-expressing cancer cell line (U937) than procaspase-3 low-sensitive cancer cell line (MCF-7). Caspase-3 activity evaluation showed that coumarin derivatives bearing benzothiazole showed remarkable caspase-3 activation activity, among them, compound 5f displayed the strongest activity with 93% degree. Flow cytometric assay revealed that compound 5f could inhibit proliferation of tumor cells by inducing apoptosis. Procaspase-3 activity assay showed that compound 5f showed strong procaspase-3 activation activity.