N-3-o-toluyl-fluorouracil (TFu) was a potent water-insoluble prodrug of 5-fuorouracil (5-Fu). To improve the solubility of TFu, TFu loaded nanosuspension (TFu-LNS) was prepared by high-pressure homogenization method. The results of in vitro release studies showed that 5-Fu was sustained released from TFu-LNS. Then in vitro antitumor activity of TFu-LNS in terms of antiproliferative activity, induction of apoptosis and G1 cycle arrest on human breast adenocarcinoma cell line (MCF-7) and human gastric carcinoma cell line (BOO) was evaluated. The results of MU assay showed that TFu-LNS exhibited higher antiproliferative activity against MCF-7 and BGC cells than TFu DMSO-water solution and 5-Fu solution. The apoptosis induced by TFu-LNS was assessed by Annexin V-FITC/PI double staining and Tunnel assay. And the results of two methods both clearly indicated that the superiority of TFu-LNS to TFu DMSO-water solution and 5-Fu solution in increasing the apoptosis rate of MCF-7 and BGC cells. The results of flow cytometric (FCM) analysis demonstrated that TFu-LNS could induce G1 cycle arrest of MCF-7 and BGC cells. Furthermore, in vivo pharmacokinetics study in Wistar rats indicated that TFu-LNS was capable of increasing the parameters of AUC(0-infinity) and MRT significantly by sustained releasing 5-Fu. Therefore, the overall results suggested that the TFu-LNS could enhance anti-tumor effect and hold great potential to be developed for cancer treatments.