Abstract: Microwave backhaul system is one of the primary means for the signal backhaul in broadband wireless communication base station systems. This paper experimentally analyzes and studies on the nonlinear characteristics of a 19GHz microwave backhaul system’s transmitter. And the digital predistortion technique based on the lookup table model is utilized to linearize the transmitter. In order to meet the needs of the signal transmission for the high capacity wireless base stations, the exponentially weighted moving average (EWMA) algorithm is used to extract the static nonlinear characteristics of the transmitter. A threecarrier WCDMA signal is used in the experimental validation. The experimental results show that the thirdorder intermodulation distortion (IMD3) can be improved over 23dB when the transmitter is linearized with the lookup table predistorter. Consequently, a simple lookup table predistortion technology can effectively improve the linearity of the microwave backhaul system transmitter. At the same time, the microwave power amplifier can operate in a higher output power, the transmission distance can be increased, and the production costs also can be reduced.