Ultra-wideband（UWB） radio technology is a new communication mode which is developing rapidly without intermediate frequency and radio frequency circuit

as well as it has a special significance on reducing sensor’s volume and loss

so it is especially suitable for wireless sensor networks（WSNs）.A single channel is divided into many slots as subchannels for nodes by using the physical characteristics of UWB signals.The relation of node transmission probability and packet collision probability under the different numbers of subchannels in WSNs is analyzed.This thesis points out that it is beneficial to reduce the packet collision probability under multi-channel.