A multifunctional endoscopic system for cavity inspection and treatment, comprising an internal incision working hand piece; an internal incision piece, arranged to snap-fit fixedly on the internal incision working hand piece, an endoscope, arranged to insert into the internal incision working hand piece from a rear end of the internal incision working hand piece, wherein a head part of the endoscope is snap-fitted on the rear end of the internal incision working hand piece, and an extension part of the endoscope passes through an inner cavity of the internal incision working hand piece and extends from a front end of the internal incision working hand piece; an endoscope sheath, snap-fitted on the front end of the internal incision working hand piece, wherein the internal incision piece and the extension part of the endoscope are axially sleeved in the endoscope sheath, wherein the internal incision working hand piece comprises: a fixed hand piece; an operation handle, arranged on the fixed hand piece and used to push the internal incision piece to move forward and back axially along the extension part of the endoscope, and a V-shape resilient piece for resetting the operation handle; wherein, a channel is formed between the fixed hand piece and the operation handle for the extension part of the endoscope to pass through, characterized in that a mounting slot is formed between the fixing hand piece and the operation handle for fixing the internal incision piece, and a limiting block is arranged on a side of the operation handle close to the fixed hand piece and protruded therefrom, so as to be against a side wall of the fixed hand piece during operation, and a groove for receiving the limiting block is arranged on the operation handle, and the limiting block is rotatably arranged in the groove. an internal incision working hand piece; an internal incision piece, arranged to snap-fit fixedly on the internal incision working hand piece, an endoscope, arranged to insert into the internal incision working hand piece from a rear end of the internal incision working hand piece, wherein a head part of the endoscope is snap-fitted on the rear end of the internal incision working hand piece, and an extension part of the endoscope passes through an inner cavity of the internal incision working hand piece and extends from a front end of the internal incision working hand piece; an endoscope sheath, snap-fitted on the front end of the internal incision working hand piece, wherein the internal incision piece and the extension part of the endoscope are axially sleeved in the endoscope sheath, wherein the internal incision working hand piece comprises: a fixed hand piece; an operation handle, arranged on the fixed hand piece and used to push the internal incision piece to move forward and back axially along the extension part of the endoscope, and a V-shape resilient piece for resetting the operation handle; wherein, a channel is formed between the fixed hand piece and the operation handle for the extension part of the endoscope to pass through, characterized in that a mounting slot is formed between the fixing hand piece and the operation handle for fixing the internal incision piece, and a limiting block is arranged on a side of the operation handle close to the fixed hand piece and protruded therefrom, so as to be against a side wall of the fixed hand piece during operation, and a groove for receiving the limiting block is arranged on the operation handle, and the limiting block is rotatably arranged in the groove. a fixed hand piece; an operation handle, arranged on the fixed hand piece and used to push the internal incision piece to move forward and back axially along the extension part of the endoscope, and a V-shape resilient piece for resetting the operation handle; wherein, a channel is formed between the fixed hand piece and the operation handle for the extension part of the endoscope to pass through, characterized in that a mounting slot is formed between the fixing hand piece and the operation handle for fixing the internal incision piece, and a limiting block is arranged on a side of the operation handle close to the fixed hand piece and protruded therefrom, so as to be against a side wall of the fixed hand piece during operation, and a groove for receiving the limiting block is arranged on the operation handle, and the limiting block is rotatably arranged in the groove.