A security check method includes: pre-creating at least four concurrently operating threads, one thread being responsible for movement control and data acquisition, one thread being responsible for imaging processing, one thread being responsible for interface displaying, and one thread being responsible for target detection and recognition; then the four concurrently operating threads divide original echo data of a human body to be checked into data of a plurality of adjacent overlapped azimuthal segments during data processing and perform individual processing on the data of each azimuthal segment. The security check system includes a thread creating unit, a first thread parallel unit, a second thread parallel unit, a third thread parallel unit, a fourth thread parallel unit, and a thread loop control unit. Because subsequent data processing is not required to be performed after the acquisition of all data is completed, the time for a security check process is reduced.