Abstract: The structural health monitoring of the wind turbine blade is an urgent problem to be solved in wind energy area. This paper analyzed techniques of damage detection for the wind turbine blade and studied the method to monitor the structural health of them based on the acoustic emission sensor array. In the monitoring system PZT sensor array was designed and arranged in areas of high damage probability. Loading to the blade was changed at step of 20% of the maximum designed loading, and the acoustic signal was collected and analyzed so as to determine the damage area based on statistics of acoustic wave hits. This method has the advantages of high sensitivity, accurate location, and real-time detection, thus is a promising method in practical applications.