The invention discloses a double-vibration exciter synchronous phase locking method and a device, wherein the device comprises two vibration exciters running in parallel in opposite directions, 2n (n is positive integer within 10) external gearing spur gears with the speed ratio of 1:1 are arranged to constitute a transmission pair, and the first spur gear of the transmission pair is connected with the main shaft of the first vibration exciter through a first elastic coupler and the last spur gear of the transmission gear is connected with the main shaft of the second vibration exciter through a second elastic coupler; a phase locking mechanism is mounted between the first spur gear or the last spur gear and the shaft of the gear, the phase locking mechanism can adjust a relative positionof the gear and the shaft in a rotating direction and locks the relative position. The device forcibly synchronizes the two vibration exciters by means of the gears, thereby eliminating the phase difference of the vibration exciters during operation, equalizing exciting force output and achieving steady-state excitation.