The invention discloses a transient electromagnetic method for detecting land Japanese abandoned chemical weapons. The method comprises the steps that a known and precisely positioned point without any obstructions and signal interference in the surrounding is selected, and a base station and a moving station are erected at the point; the moving station and the base station are connected and synchronized; a standard point is selected for coordinate correction; after the coordinate correction is completed, setting-out is carried out; a detection coordinate system is established; the base station is fixed; relative coordinates are input; the coordinate axis value and the positive direction are determined according to a detection scheme; a transient electromagnetic instrument is used for detecting in a detection area; the position of a measuring line and the distance between measure points are determined according to the detection scheme; the measurement network of the whole area is drawn; the position of each measure point is marked, and successive measurement is carried out until the measurement of the whole detection area is completed; a multi-channel map is drawn based on the detection data of the whole area; and according to the measured data, a full map of the apparent resistivity of the detection area is drawn to determine an abnormal area.