Silk Road is a famous ancient trade channel from Asia to Europe. The study on dynamic mechanism of the towns along the Silk Road is the basis of environmental protection, resources allocation and sustainable development. In this paper, Based on the achievements of previous studies, the author proposed five key factors about towns' evolution by AHP, including ecological environment, political stability, transportation stop, commercial trade and multi-cultural. Furthermore, the mechanism of the five factors is analyzed, which is very meaningful to the comprehension of man-land relationship, so as to the exploration of man-nature interaction harmoniously.