Disclosed is a radiating matrix and a sealed PTC thermister heater. The radiating matrix includes a cavity body with a containing cavity, a plurality of radiating fins are fixed in the middle of the external surface of the top and the external surface of the bottom of the cavity body; a first positioning rib extending along a length direction of the cavity body is arranged at the upper part and the lower part of the inner wall of the left side of the cavity body in the containing cavity respectively, correspondingly, a second positioning rib extending along a length direction of the cavity body is arranged at the upper part and the lower part of the inner wall of the right side of the cavity body in the containing cavity respectively, the internal surface of the left side of the containing cavity between the two first positioning ribs is an outwards convex arc surface, the internal surface of the right side of the containing cavity between the two second positioning ribs is also an outwards convex arc surface
