The propagation characteristics of Ultra-WideBand(UWB) indoor signals are analyzed,and multi-path components are found to arrive in clusters.The general rule of channel model parameters is studied on the basis of measurement data.Results show that the arrival rate of cluster is far less than that of the diameter,while the attenuation coefficient of cluster is greater than that of the diameter.The parameters of IEEE 802.15.3a channel model are modified in the CM2 environment.Simulation results show that the modified CM2 channel model is superior to the original model,which can better reflect the clustering characteristics of multi-path component arrival.The fitting result indicates a good agreement between measurement data and the modified model.