Abstract: A simple method was presented to fabricate tool for hot embossing by modifying PDMS （polydimethylsiloxane） with nano particles,such as SiO₂,TiO₂. The effect of the mix ratio of PDMS and these two kinds of nano particles on hot embossing as well as the optimum conditions was investigated. In order to improve the efficiency of hot embossing,primary analysis was made by analyzing the variation of Young’s modulus and thermal coefficient expansion of modified PDMS which were studied by thermal analyzer. This modified PDMS was used to fabricate mold by rapid prototyping,which was then used to fabricate polymethyl methacrylate （PMMA） mircofludic chips by hot embossing. Compared with the conventional hot embossing mold,such as metal mold and silicon mold,this modified PDMS mold is of excellent duplicate of microstructures,very rapid,low cost,and reduction in complexity,what’s more,the molds are released easily,and have has a good reproducibility.