A method and an apparatus for detecting a magnetic signal of paper money. By using detecting a magnetic track and repairing an abnormal magnetic track, the detection method solves the phenomenon of the abnormal magnetic track, and greatly improves the recognition accuracy rate and the receiving rate of a paper money recognition apparatus. The detection method comprises: S1: acquiring original data of a paper money magnetic signal; S2: performing abnormal magnetic track detection on the original data to obtain a detection result; S3: if the detection result is an abnormal magnetic track, performing step S4 and step S5, otherwise, performing step S6; S4: repairing the original data according to a preset repair rule to obtain repaired data; S5: comparing the repaired data with a preset standard value to obtain a recognition result; and S6: comparing the original data with the preset standard value to obtain a recognition result.