Abstract: The invention relates to a fast alignment telescopic sight for use in connection with firearms to improve sighting accuracy. It comprises a tube, an optical sighting system, and an alignment unit. An alignment mark is provided in the target image plane of the optical sighting system, and is coupled to the tube through an adjustable connection unit. The adjustable connection unit comprises a base coupled to the tube, an adjustable positioning support mounted in the base, and a rotation pin passing through and secured to the adjustable positioning support. The alignment mark is secured to the front end of the rotation pin. The invention can be used for adjusting the alignment mark in arbitrary directions to ensure the alignment mark to be exactly located in the target image plane and at the center of the field of view against various manufacturing errors. The invention features simple construction, reliable performance and low manufacturing cost.