The invention discloses a total reflection type Terahertz-wave scanning imaging device. A plurality of ellipsoidal lenses are adopted to form a polyhedron focusing scanning lens, wherein the ellipsoidal lenses are symmetrically arranged relative to the central axis through a focus in an ellipsoid on which the ellipsoidal lenses are arranged. When the polyhedron focusing scanning lens rotates to scan an imaged object, each ellipsoidal lens on the ellipsoid can converge Terahertz waves received from a frame scanning plane mirror to the other focus, deflection of a converging point cannot be caused by vibration of the ellipsoidal lens, so that imaging quality is improved. When the polyhedron focusing scanning lens rotates, through matching with the frame scanning plane mirror, each ellipsoidal lens which passes by a reflective light path of the frame scanning plane mirror can carry out one row of scanning on the imaged object in a transverse range, and the polyhedron focusing scanning lens rotates for a circle to obtain N rows of pixel data. Compared with a scanning imaging device with one ellipsoidal lens, the total reflection type Terahertz-wave scanning imaging device greatly improves the speed of scanning and imaging.