The present disclosure relates to a mechanical transmission mechanism and a base station antenna. The mechanical transmission mechanism extends between an actuator and a phase shifter of the base station antenna, and comprises: a first rod driven by the actuator; a second rod for moving a movable element of the phase shifter, the second rod having a proximal end and a distal end; and a link for connecting the first rod and the second rod, the link having a proximal end and a distal end and including a first connecting element that movably connects the first rod with the link and a second connecting element that fixedly connects the second rod with the link; wherein position of the distal end of the second rod relative to the proximal end of the link is adjustable, so that a length of the second rod extending from the proximal end of the link is adjustable, thereby eliminating a virtual displacement caused by mechanical tolerances from the actuator, the mechanical transmission mechanism, and the phase shifter during adjustment of the phase shifter.