Successful chemotherapy needs to reduce the toxic side effects against normal tissues and avoid the detriments caused by intolerable solvents. Drug delivery systems using soluble polymeric nanoparticles tend to be the focus. In the current study, core-shell structure nanoparticles were prepared from block copolymer of methoxy poly(ethylene glycol)-polycaprolactone (mPE-PCL). Paclitaxel (PTX) and berbamine (BA) were incorporated into mPEG-PCL nanoparticles. It was found in our study that PTX and BA can be incorporated into the nanoparticles with high encapsulation efficiency. In vitro release study showed that PTX and BA were released from nanoparticles in a sustained manner. In vitro cytotoxicity studies indicated that PTX/BA coloaded nanoparticles (PTX/BA-np) show dose- and time-dependent cytotoxicity again BGC823 cells. Furthermore, intratumoral administration was applied to improve the tumor-targeted delivery in the in vivo evaluation. Compared with free drugs, PTX/BA-np exhibited superior antitumor effect by delaying tumor growth when delivered intratumorally. These results suggest that PTX/BA-np are effective to inhibit the growth of human gastric cancer and merit more research to evaluate the feasibility of clinical application.