Disclosed is a deflector disc of a disc tube membrane module, including a deflector disc body, radial water distribution ribs, an inner support ring and an outer support ring. Bulges are arranged on the front and back sides of the deflector disc body; first and second ends of the radial water distribution rib are respectively fixedly connected with an inner edge of the deflector disc body and an outer edge of the inner support ring, an annular boss is arranged on the front side of the inner support ring, a seal ring groove is respectively arranged at corresponding positions of the front and back sides of the inner support ring, multiple yielding water collecting grooves are annularly and uniformly distributed on the inner surface of the inner support ring; an inner edge of the outer support ring is fixedly connected with an outer edge of the deflector disc body.