To suppress the effect that differences of channel in different indoor environment bring to mitigation of ISI for UWB receiver,an adjustable observation window length-fractionally spaced linear equalization ( AOWL-FSLE) equalization receiver is proposed in this paper. The receiver can adaptively select the observation window length according to difference of channel. Simulation results show that when channel changed, compared with fixed observation window length-fractionally spaced linear equalization (FOWL-FSLE) equalization receiver,the AOWL-FSLE equalization receiver can achieve better BER performance,because it can suppress the effect of ISI more effectively.