The algorithm of interference detection for Multi-band Ultra-wideband communication system is analyzed and discussed in this paper. A modified scheme named parallel multi-band UWB is presented to improve the data transmission speed of the traditional MB-UWB scheme. In order to meet the requirement for high data transmission speed, an orthogonal operation of sub-pulse is designed. The performance of interference suppression for parallel multi-band ultra-wideband communications is mathematically analyzed and described. Based on this new scheme, a new algorithm named parallel sub-pulse interference detection is proposed. This new algorithm can be realized in low level sample rate. Mathematic analysis and computer simulation for this new algorithm are made. The simulation results show that the new algorithm can detect the coexisting interference effectively in low sample rate and improve the BER performance of parallel multi-band UWB communication system evidently in combination with the interference suppression measures.