Abstract: Investigates the problem of integration time optimization for ultra-wideband(UWB) energy detection receivers(ED-UWB). Based on the energy detection model, diffusion model for UWB indoor propagation and central limit theorem, a new estimation method of optimal integration time under multipath environment is proposed. The criteria of minimizing the average bit error probability (BEP) is adopted. It is shown that under the environment of low SNR, the optimal integration time is related with the power decay time constant, while under the environment of high SNR, a curve fitting amendment is adopted. Theoretical analysis and simulation proved the effectivity of the algorithm.