A handheld radiation image detecting system and an operation method thereof are provided. The handheld radiation image detecting system includes a handheld device including a radiation emitter and a first transceiver and a sensing device including a radiation image sensor and a second transceiver. The first transceiver is coupled to the radiation emitter and used for generating a first wave with directionality. The second transceiver is used for receiving the first wave and for generating a second wave with directionality, and the first transceiver is used for receiving the second wave.
