As the foremost historian who has conducted overall systemic research on the system in the Wei, Jin, Northern and Southern Dynasties, LV Si-mian has contributed profound works concerning the law in the Northern Wei Dynasty. As an ethnic regime that entered the Central Plain, the Northern Wei Dynasty experienced a great many juridical practical controversies between the traditional customary law of Xianbei （an ancient nationality in China） and the criminal law written in Chinese characters. The solution of various controversies was entangled with the Sinicization of Xianbei people. Hence, the Northern Wei authorities showed profound political wisdom in the process of solving these problems, which exerted great impact on later generations.