Multipath energy capture and inter-symbol interference (ISI) are two intractable problems in high-data-rate Ultra-wideband (UWB) systems. To tackle the problems and simplify the receiver, we propose an adaptive interference avoidance scheme based on Pre-RAKE combining technique. The symbol repetition period (SRP) is regarded a changeable parameter in an ordered set to avoid severe interference paths and guarantee high data-rate. The set is known to both the transmitter and receiver. The index of the selected SRP is then sent to the receiver to coordinate the transmitter and receiver. The SRP can be updated adaptively according to the variations of the channels. Both theoretical analysis and simulations show that the ISI is mitigated and the transmission rate is improved simultaneously compared to the constant SRP transmission scheme.