In the seeker gate, whether the guidance signal can enter and whether the high-frequency interference is advanced is a probability problem. The probabilistic analysis method was used to discuss the probability (guidance probability) of the guided laser entering the gate and the probability (advance probability) of the first pulse of the high-frequency laser leading the guided laser. By studying the relationship between the guidance probability and the standard deviation of the laser light extraction time (standard deviation of laser timing) and the relationship between the guidance probability and the gate width, it was concluded that when the gate width was 6.18 times the standard deviation of the laser timing, the guided laser can be considered to completely enter the seeker gate. Based on the guidance probability, the relationship between the advance probability and the number of high-frequency pulses in the gate was obtained; the relationship between the advance probability and the gate width at different high-frequency laser frequencies was gained. When there were 4 high-frequency pulses in the gate, the advance probability was 98.21%. Therefore, from the laser guidance, the seeker gate width can be selected according to the standard deviation of laser timing to achieve accurate guidance; from the high-frequency interference effect, the high-frequency interference frequency can be determined according to the seeker gate width to achieve effective interference.