Drug delivery by nanocarriers requires characterizations of suitable particle size, high drug loading and safety. In this work, we prepared an amphiphilic dendrimer modified PEG-PLA mixed nanoparticles(NPs) by a double emulsion-solvent evaporation(DESE) method. The particle size and drug encapsulation efficacy(EE) were compared to evaluate and optimize the preparation parameters. The mixed NPs had average size ranging from(102±1) nm to(137±5) nm, and the zeta potential turned to positive with incorporation of the amphiphilic dendrimer. The NPs showed different EE of docetaxel(DTX) and paclitaxel(PTX) with higher affinity to more lipophilic PTX. The blank mixed NPs showed little cytotoxicity, and the DTX-loaded NPs could effectively facilitate the antiproliferation activity on PC-3 cells. The NPs could be used as an effective drug delivery system, and its anti-tumor effect is worthy of further study.