A series of triaminotriazine derivatives (compounds 5a-f, 6a-x, and 7a-g) was designed, synthesized, and evaluated for their inhibition activities to colorectal cancer (CRC) cell lines (HCT-116 and HT-29). Most of the synthesized compounds demonstrated moderate anti-proliferatory effects on both HCT-116 and HT-29 cell lines at the concentration of 10 microM. The inhibitory activities against HCT-116 and HT-29 cell lines were discussed to develop the structure-activity relationships of this new series. Compounds 6l and 6o exhibited prominent inhibition activities toward HCT-116, with IC50s of 0.76 and 0.92 microM, respectively. The in vivo antitumor studies and pharmacokinetics of compound 6l showed that it might be a promising new hit for further development of antitumor agents.