从网络联结国的邻接矩阵出发，提出在Ｉｎｔｅｒｎｅｔ网络环境下直接构造网络最短主树的一种方法──节点子树剪枝法．在无约束条件和有约束条件（如转接数、传输链路带宽限制情况下），给出Ｉｎｔｅｒｎｅｔ最短主树算法．该算法用于计算Ｉｎｔｅｒｎｅｔ环境下可扩展的ＩＰ路由表具有较高效率． Based on the adjacency matrix of network-connected countries, a method of constructing the shortest main tree of network directly in Internet environment is proposed, which is a node sub-tree pruning method. Under the condition of no constraint and constraint (such as the number of transfer and the limit of bandwidth of transmission link), the Internet is the shortest primary tree algorithm. The algorithm is used to calculate the Internet environment scalable IP routing table with high efficiency.