The present invention relates to the radiation detection field, in particular to a scan method and a device thereof which are applied to a van container radiation monitoring system and a safety field auditing system. The invention provides an active-passive combination scan method and the device thereof which are applied to the van container radiation monitoring system, a manual control knob support arranged at the front of a vertical detection arm in a scan channel provides an optional passive initialization ray scanning mode for a driver of a container truck. After a detection vehicle is parked at a specified place in a detection area, the mode that the driver presses down a manual control button to start the detection or the driver gets off for leaving the detection area to wait for the detection is selected. The scan method and the device thereof provided by the present invention not only ensure the personnel safety of the missionary, but also are convenient and fast, thereby greatly improving the speed of the detection.