To evaluate the performance of 1394b bus being unmatchable at node transmission rate, the reliability of the typical stacktree topology is studied and analyzed, and an asynchronous communication model of 1394b bus is put forward in OPNET environment. First, hierarchical model of the node of 1394b is designed，and then, bus initialization, treeidentification and selfidentification are performed to complete the bus configuration by the processing module of application layer. Media access control layer is responsible for asynchronous arbitration and the process of inflow/outflow message. Finally, the utilization rate of the 1394b bus, the number of asynchronous arbitration and the endtoend timedelay characteristic can be achieved through simulation on OPNET. The experimental results show that the natural priority whose nodes are higher than the others can take the lead in using the bus, and at the same time, the ETE average delay is increased with the increase of topological distance increases between nodes.