Pipe joint assembly, comprising a tube and a pipe joint (2, 3, 4, 5) capable of preventing the slipping -off of the tube, wherein the tube is made of PFA; the pipe joint (20, 30, 40, 50) is made of fluororesin, coupled to one end of the tube, configured to fasten the end of the tube, and includes a joint body (2,3,4,5), a union nut (26,36,46,56), and a fixed ring (27,37,47,57); wherein the end of the tube is inserted through a tapered opening (261, 361, 461, 561) of the union nut (26,36,46,56) and a central bore (279,379,479,579) of the fixed ring (27,37,47,57) and is formed with a flared portion, the flared portion including a cone tube and a cylindrical tube; wherein the joint body (20,30,40,50) includes a through hole to direct the fluid and has a tube connecting portion (200,300,400,500) at one end thereof for connecting with the union nut (26,36,46,56) and the tube; wherein the tube connecting portion (200,300,400,500) includes a conical surface (201, 301, 401, 501), a cylindrical surface (202,302,402,502), and a locking thread (204,304,404,504), the conical surface (201, 301, 401, 501) and the cylindrical surface (202,302,402,502) is configured to be coupled to the cone tube and the cylindrical tube of the tube, and a conical angle ε defined between the conical surface (201, 301, 401, 501) and an axial line of the pipe joint (2,3,4,5) comes in specification of 50°≦ε<90°; and wherein an inner diameter of the union nut (26,36,46,56) includes a threaded part (266,366,466,566) and a tapered end (260,360,460,560), the threaded part (266,366,466,566) is configured to be securely locked with the locking thread (204,304,404,504) of the tube connecting portion (200,300,400,500), and a center of the tapered end (260,360,460,560) is provided with the tapered opening (261,361,461,561); characterized in that the fixed ring (27,37,47,57) is placed inside the union nut (26,36,46,56), one end of the fixed ring (27,37,47,57) is provided with an annular bulging curved surface (270,370,470,570), with a compression ring edge (2701,3701,4701,5701) formed thereon, and the other end of the fixed ring (27,37,47,57) is provided with another annular bulging surface with a stress ring edge (2702,3702,4702,5702), such that the fixed ring (27,37,47,57) has a symmetrical or asymmetrical near-trapezoid cross-section structure; and that the inner diameter of the union nut (26,36,46,56) includes an inner recess (262,362,462,562), with an applied force ring edge (2622,3622,4622,5622) formed thereon, wherein the stress ring edge (2702,3702,4702,5702) is configured to abut against the applied force ring edge (2622,3622,4622,5622) to form a coupling sliding surface; and that the compression ring edge (2701,3701,4701,5701) is configured to abut against a tube wall of the cone tube to form a sealed surface on the conical surface (201, 301, 401, 501) of the tube connecting portion, with a compression angle β of specification 55°≦β≦75°, wherein the compression angle β is defined between the annular bulging surface (270,370,470,570) and an inner surface of the fixed ring (27,37,47,57); and that the inner recess (262,362,462,562) of the union nut (26,36,46,56) is provided with a skew surface (2623,3623,4623,5623) adjacent to the applied force ring edge (2622,3622,4622,5622) such that an axial gap (2624,3624,4624,5624) is formed between the skew surface (2623,3623,4623,5623) of the union nut (26,36,46,56) and the another annular bulging surface (270,370,470,570) of the fixed ring (27,37,47,57), the axial gap (2624,3624,4624,5624) restricting contact area of the coupling sliding surface and thereby lowering frictional risk of sliding on the sealed surface; and that a lead angle space is formed at a fringe of the central bore (279,379,479,579) adjacent to the end of the fixed ring (27,37,47,57) that is provided with the compression ring (2701,3701,4701,5701); and that the fixed ring (27,37,47,57) is maintained at a center position by means of a guiding mechanism, wherein once a compression force is applied on the coupling sliding surface in a direction toward the compression ring (2701,3701,4701,5701) and the sealed surface, an accumulated annular deformation is generated on the tube wall of the cone tube, wherein an applied force included angle θ is defined between the compression force and a normal line of the conical surface (201,301,401,501) and comes in specification of 0°<θ≦15°.