A rotary compensating device used in a pipe under high pressure comprises an inner pipe (1), a sealing gland (3), a sealing seat (5) and a connecting pipe (7). One end of the inner pipe (1) is inserted into the connecting pipe (7), and the connecting pipe (7) is fixedly connected with one end of the sealing seat (5) and is installed on the outer surface of the inner pipe (1). The inner pipe (1) is provided with an annular outer flange (8), and the sealing seat (5) is provided with an annular inner flange (9). The sealing gland (3) is installed on the outer surface of the inner pipe (1) and inserted into the other end of the sealing seat (5) to abut against a torus sealing member (4). The sealing gland (3) connects with the sealing seat (5) via a connecting member (2). A sealing cavity is formed between the sealing seat (5) and the inner pipe (1), and an end face sealing member (6) is installed in the sealing cavity.