Disclosed is a method for analyzing a blind zone of a magnetic detection method that can provide a complete distribution map of the detection blind zone within the entire zone of the magnetic target. The method comprises the first step of establishing a complete magnetic detection model to obtain calculated position and magnetic moment of a magnetic target that is detected by a magnetic gradiometer. The second step involves establishing a direction-attitude-sphere model to represent the entire zone of the magnetic target. The third step involves expanding the direction-attitude-sphere to a planar map layered by latitude and calculating success detection rates within the planar expansion map. Finally, the distribution map of the magnetic detection blind zone in the entire zone is visually presented in the planar expansion map and a complete distribution rule of the entire detection blind zone is thus obtained. This blind zone analysis method is applicable to any magnetic detection method and can provide a visual presentation of the entire detection blind zone. The knowledge of the detection blind zone can be applied to guide practical magnetic detection to avoid the detection blind zone so as to increase the detection accuracy.