A series of novel 1,2,4-triazole derivatives incorporating benzisoselenazolone scaffold were designed, synthesized and evaluated for their in vitro antiproliferative activities against human cancer cell lines SMMC-7721, Hela, A549, and normal cell lines L929 by CCK-8 assay. The preliminary bioassay results demonstrated that most of the tested compounds 3a-3n exhibited antiproliferation with different degrees, and some compounds showed better effects than positive controls ethaselen and 5-fluorouracil (5-FU) against various cancer cell lines. Among these compounds, compounds 3b and 3c displayed highly effective biological activities against SMMC-7721cells with IC50 values of 6.02 and 6.01 μM, respectively. Compound 3n showed significant antiproliferative activities against Hela cells with IC50 value of 3.94 μM. Compound 3n exhibited the best inhibitory effect against A549 cells with IC50 value 9.14 μM. Furthermore, most of the tested compounds showed weak cytotoxic effect against the normal cell lines L929. The pharmacological results suggest that the substituent groups are vital for improving the potency and selectivity of this class of compounds.