The utility model provides a radiation imaging detector, comprising a plurality of detection units which are arranged in a mode of opposite alternation of twin rows. Each detection unit which adopts a mode of a bismuth germanate crystal coupled with a photomultiplier comprises the bismuth germanate crystal, a crystal sleeve, a photomultiplier, a photomultiplier sleeve, a tube holder, a circuit module and an interface base plate, wherein the photomultiplier, the tube holder and the circuit module are arranged in the photomultiplier sleeve, the bismuth germanate crystal is covered by the crystal sleeve and is coupled with the photomultiplier in the photomultiplier sleeve, the other end of the photomultiplier sleeve is provided with the interface base plate, and the photomultiplier is connected with the interface base plate through the tube holder and the circuit module. The radiation imaging detector which is suitable for the radiation imaging detection under the condition of a low-intensity radiation source can reduce the radiation effect on the environment and the ionizing radiation injury on personnel, and has good resistance to extreme climate, low manufacture cost, as well as good economic and social benefit.