The ascertainment of foreign law is the basis of hearing foreign civil and commercial cases in the process of the Silk Road Economic Belt and the 21st-Century Maritime Silk Road1513734. Because current legislative regulation about ascertainment of foreign law is slightly rough and theoretical and practical problems exposed is also more prominent，We must determine the main responsibility of foreign law，formulate the subsequent remedial measures，establish the judge professional learning system and platform，build judicial assistance mechanism of People’s Courts and schools in order to guarantees the Belt and Road，enhance international referee credibility.