The invention discloses an endoscopic imaging device and a method for obtaining a fluorescence lifetime distribution image. The endoscopic imaging device comprises a laser transmission module, an endoscopic module and a fluorescence lifetime imaging module; the laser transmission module comprises a laser device, a dichroscope, a scanning galvanometer and a lens set; the endoscopic module comprisesan image transmission fiber bundle and a micro graded refractive index prism; lasers emitted by the laser device are sequentially transmitted through the dichroscope, the scanning galvanometer, the lens set and the image transmission fiber bundle and are emitted from the micro graded refractive index prism; the fluorescent lifetime imaging module comprises a light filter, a single-photon counterand a controller, the light filter is arranged between the dichroscope and the single-photon counter, and the controller is connected with the single-photon counter, the laser device and the scanninggalvanometer; light emitted from the micro graded refractive index prism sequentially passes through the image transmission fiber bundle, the lens set, the scanning galvanometer, the dichroscope and the light filter and reaches the single-photon counter. By means of the device, fluorescence lifetime detection can be applied to clinical detection, and disease diagnosis is facilitated.