The invention relates to an automatic limiting device and a maintenance mechanism provided with the same. The automatic limiting device comprises a moving part, a fixing portion, a guide rail and a limiting portion, wherein the fixing portion is arranged on the side face of the guide rail, the limiting portion is arranged on the guide rail, and the moving part is arranged on the guide rail and can move on the guide rail. The automatic limiting device further comprises a spherical body and an elastic part, and the spherical body is connected with the elastic part. The fixing portion comprises a supporting end, the spherical body and the elastic part are arranged between the guide rail and the supporting end, a through hole is formed in the guide rail, and at least one part of the spherical surface of the spherical body penetrates through the through hole. The automatic limiting device can prevent a sliding door from getting loose freely, does not need to be operated or locked manually, and is convenient to use. Meanwhile, a manual limiting device does not need to be arranged, and the overall attractiveness of the maintenance mechanism is improved.