The invention discloses a disposable hard endoscope sleeve lens and a lens alignment method. The lens comprises a rigid head and a flexible sleeve; a connecting end of the flexible sleeve is connected with the rigid head, and the other end of the flexible sleeve is an open free end; a 1:1 nonopaque lens group is arranged in the head to form a sealed front end; the connecting end of the flexible sleeve is provided with a first rigid ring, the free end of the flexible sleeve is provided with a second rigid ring, and first and second limiting devices are arranged on the first and second rigid rings; the flexible sleeve is sheathed on an outer surface of a hard endoscope; and the first and second rigid rings locate the lens group on a position overlapped with the main optical axis of the lens group of the hard endoscope by means of the first and second limiting devices. The method comprises the following steps: keeping the first rigid ring to be coaxial with the lens group through the rigid head; and keeping the first rigid ring to be coaxial with the second rigid ring through the first and second limiting devices. By adoption of the sleeve lens and the alignment method thereof provided by the invention, the sterilization and imaging problems of the existing endoscopes are solved.