A sealing structure, comprising an inner pipe and at least one sealing ring, wherein an outer wall of the inner pipe is provided with at least one sealing groove, each sealing ring is nested in a corresponding sealing groove, and the inner pipe can be sealingly connected, through compressive deformation of the sealing ring, to a pipe inserted outside the inner pipe; the sealing ring comprises a main body and a lip extending along an inserting direction of the pipe from a radially inner side of a first end of the main body; the sealing groove comprises a first sealing groove and a second sealing groove, the lip is nested in the first sealing groove, and the main body is nested in the second sealing groove; and a step for preventing an axial movement of the main body is formed between the first sealing groove and the second sealing groove; when the sealing ring is in a non-compressed state, an outer diameter of a second end of the main body is less than an inner diameter of the pipe, a maximum outer diameter of the lip is greater than the inner diameter of the pipe, and an axial length of the lip is less than a width of the first sealing groove; and a peripheral wall of the sealing ring is provided with a guide surface for guiding insertion of the pipe, and the guide surface is disposed between a position indicated by the maximum outer diameter of the lip and the second end of the main body; and when the sealing ring is compressed by the pipe, the lip is squeezed, and has a first sealing surface in contact with a bottom surface of the first sealing groove and a second sealing surface in contact with an inner wall of the pipe; characterized in that, when the sealing ring is in the non-compressed state, an axial length of the main body is less than a width of the second sealing groove. the sealing ring comprises a main body and a lip extending along an inserting direction of the pipe from a radially inner side of a first end of the main body; the sealing groove comprises a first sealing groove and a second sealing groove, the lip is nested in the first sealing groove, and the main body is nested in the second sealing groove; and a step for preventing an axial movement of the main body is formed between the first sealing groove and the second sealing groove; when the sealing ring is in a non-compressed state, an outer diameter of a second end of the main body is less than an inner diameter of the pipe, a maximum outer diameter of the lip is greater than the inner diameter of the pipe, and an axial length of the lip is less than a width of the first sealing groove; and a peripheral wall of the sealing ring is provided with a guide surface for guiding insertion of the pipe, and the guide surface is disposed between a position indicated by the maximum outer diameter of the lip and the second end of the main body; and when the sealing ring is compressed by the pipe, the lip is squeezed, and has a first sealing surface in contact with a bottom surface of the first sealing groove and a second sealing surface in contact with an inner wall of the pipe; characterized in that, when the sealing ring is in the non-compressed state, an axial length of the main body is less than a width of the second sealing groove.