The present application relates to a remote exposure control device, a digital radiography system and an exposing method for the system. The remote exposure control device comprises: a power source module, a sensing module electrically connected to the power source module, a processing module electrically connected to the power source module, and a communication module, wherein: the sensing module is electrically connected to the communication module and the processing module respectively; the communication module is configured to communicate with a flat panel detector (FPD) paired with a digital radiography system; and the processing module is configured to, after receiving a trigger signal sent by the sensing module, control the communication module to send an awakening instruction or a power-on instruction to the FPD, so that the FPD is awakened from a sleeping state or a power-off state to a working state. Compared with the prior arts, the remote exposure control device of an embodiment can remotely control and monitor an FPD, facilitating realizing sciagraphing by one key and improving the work efficiency of users.