The invention relates to a device, a system and a method for double-energy detection, and belongs to the field of radiation survey. The device comprises a first pixel detector array which is on the side close to a radiation source and is used for detecting radiation source photons with relatively low energy and a second pixel detector array which is on the side far away from the radiation source and is used for detecting radiation source photons with relatively high energy, wherein the first pixel detector array comprises a plurality of rows of first pixel detectors, each of the first pixel detectors comprises a first sensitive medium, a first photosensitive device, a first incident plane for radiation source incidence and a first window coupled with the first photosensitive device, and the first incident plane faces the radiation source; the second pixel detector array comprises a single row of second pixel detectors, and each of the second pixel detectors comprises a second sensitive medium, a second photosensitive device, a second incident plane and a second window coupled with the second photosensitive device; the pixel area of each second pixel detector is the same as that of multiple corresponding first pixel detectors. The invention can give consideration to the identification of effective atomic number of substances, promotion of space resolving power and strengthening of effective detection for rays at the same time.