This paper proposed a new wireless sensor network's modulation, multi-band OFDM modulation based on ultra wideband signals. The modulation used 7500(MHz) band from 3.1(GHz) to 10.6(GHz). The band was divided into thirteen same sub-bands. Each sub-band used OFDM modulation for transmission. The transmission node could adaptively choose one or more sub-bands to avoid interference according to reception node's feedback about interference sub-bands. The simulation results show that the modulation provides a good robust interference and coexistence performance. It also has low transmission power, low reception power, high-speed transmission, large system capacity and strong anti-multipath. So it is a cost-effective way to be integrated in the WSN instead of traditional radio transceiver. The modulation has good application prospect.