The bootstrap is a great technique for assessing the accuracy of parameters estimator, that have been widely applied on statistical and signal processing problems. A novel algorithm based on block bootstrap for DOA estimation in small size of snapshots is proposed in impulsive noise background. We filtered the received array signals to reduced the impact of the impulsive firstly. Then resampled the data for 1000 times to create a new matrix, therefore an arrival angle is estimated by the root-music algorithm in the conditions of confidence interval. Simulation results show that higher estimation probability and smaller mean square error can be achieved in the situation of fewer snapshots received by passive radar system than that of traditional algorithm.