Being different from the general method, a formal language and grammar, stochastic liner grammar and its representation are used to describe the topology logic of the computer network by analyzing the grammar of three elemental statuses. It can be seen that combining them may describe statuses of each node in communication and shared memory of the computer network. In this paper, it is proved that the grammar can establish only route between the start node and the terminal node in some conditions. Under conditions above if may avoid collision. The use and the limit of the grammar are presented at the end of the paper.