The invention discloses an FPGA-based photogrammetric system multi-camera dynamic synchronous exposure circuit and method. The circuit comprises a forward channel module, an FPGA processing module, a power supply module and a clock module. The forward channel module provides connection channels for all the cameras and is also connected with the FPGA processing module to transmit the acquired photographing trigger instruction of each camera. The FPGA processing module records the asynchronous time difference of the shutter action of each camera according to the acquired camera photographing trigger instruction and calculates the value of the asynchronous time difference, and delays other trigger signals according to the value of the asynchronous time difference with the last arrived shutter action signal acting as the reference so as to generate the synchronous photographing trigger signal of each camera. The power supply module supplies power to the FPGA processing module. The clock module is configured for providing a high frequency time base clock signal for the FPGA processing module.