The invention discloses a self-locking hard pipe connecting piece provided with an inner connector. The self-locking hard pipe connecting piece comprises a connecting head, wherein the connecting head comprises an outer locking sleeve, an inner connecting pipe and a movable snap ring; the outer locking sleeve is provided with a first inner wall; the inner wall of the outer locking sleeve is further provided with an annular groove; the annular groove comprises a front snap ring retaining wall, a rear snap ring retaining wall and at least two stages of groove cavities with different inner diameters; and the two stages of groove cavities comprise a first-stage groove cavity and a second-stage groove cavity. According to the self-locking hard pipe connecting piece, the outer locking sleeve is provided with at least two stages of groove cavities with different inner diameters, so that the movable snap ring is in a limited state in the first-stage groove cavity and is in a freely expanded space in the second-stage groove cavity, and the situation that under the self-locking working state, the connecting piece pushes up and presses the movable snap ring into an included angle of an acute angle for a long time to cause deformation and further affect dismantling and mounting is avoided.