The paper introduced magnetic flux leakage testing principle of wire rope flaw detector, and used finite element analysis method to analyze impact factors of detection results of wire rope flaw detector based on flux leakage testing principle, the impact factors include material of sensor parts, rope lift-off distance and number of broken wires. The analysis results show that the factors of lift-off distance and the number of broken wires have large impact on detection results of wire rope flaw detector, and the factors of angle and depth of broken wires has little impact on detection results of wire rope flaw detector.