Abstract: According to the theories of fault tree analysis (FTA), the fault tree diagram of retaining structure system with row piles is established. The probability method of combining the statistical frequency and the progressional probability of accidental excavations investigated by experts to verify the probability of bottom events is proposed. The top events according to the probability of the basis of verifying the minimal cut set are calculated. The intersecting cut set is obtained through the recursive algorithms by using the intersecting and non-intersecting in the minimal cut set. The basic events are rearranged based on the importance according to the importance analysis to find out the most influentially potential factor for the occurrence of the top events. Also, a safety evaluation report is finished, and the corresponding safety measurements are suggested.