The invention discloses a multi-camera synchronous triggering device and a control method, thereby achieving the automatic triggering of a plurality of cameras based on a GPS signal. A synchronous trigger receives GPS serial port information and a PPS signal. According to the GPS signal, the flight height, flight speed and preset overlap ratio of an aircraft are resolved according to the GPS signal, and the photographing intervals between the cameras are calculated. According to the photographing intervals, the synchronous triggering is carried out, and feedback signals exposed by the cameras are read. Moreover, the height, speed and time information of camera triggering are stored in an on-board SD card, thereby facilitating the subsequent data processing. The device irons out the defects that a conventional camera trigger cannot be corresponding to the standard time, cannot achieve the storage of data and is short of an exposure feedback signal detection loop when the conventional camera trigger is based on an off-line clock of a local timer, thereby effectively employing the GPS information to facilitate the subsequent data processing, and improving the reliability.