20(S)-uracil-1′(N)-acetic acid CPT-ester derivatives were synthesized. Several analogues exhibited superior cytotoxicity compared to CPT and TPT. 12 possessed higher in vivo antitumor activity and lower toxicity than TPT. The mechanism study revealed that 12 was a Top I inhibitor as same as TPT. 12 is a new class of antitumor clinical trial drug candidate of CPTs.