Abstract: To analyze the importance of link in directed communication networks,a method based on directed communication network to evaluate the importance of the link is to be presented in this paper.The method calculates the information amount of each link as a link weight value via transmission probability of each sub-link.Then it uses the link calculation method proposed in this paper to find out all the transmission routes of initial node and destination node,each sub-link calculates the total link weight value respectively via a weighted summation,and get valuation coefficient by taking the reciprocal value of the total weight value.According to the importance of the defined link,we can evaluate the importance of the link by evaluating the valuation coefficient of each link.A calculation example shows that this approach is feasible which can effectively evaluate the importance of the directed network link.