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 . <EOS>