The invention relates to a heat preservation concave flanged pipe fitting which comprises a base plate (1) and a pipe body (2), wherein the cross sections of both the base plate (1) and the pipe body (2) are in circular ring shapes; the bottom of the pipe body (2) is welded at the inner diameter of the base plate (1); large through holes (1.1) are formed in the base plate (1); an internal thread (2.1) is formed on the inner diameter of the pipe body (2); a heat preservation layer is arranged on the outer surface of the pipe body (2); a flange (3) is arranged at the top end of the outer wall of the pipe body (2); and a groove (4) is formed between the flange (3) and the top of the pipe body (2). The heat preservation concave flanged pipe fitting disclosed by the invention can well guarantee temperature in the pipe body, and heat is not liable to dissipate; the service life of equipment is prolonged; and connection between one set of equipment and another set of equipment and connection between one pipe body and another pipe body are firmer.