Disclosed is a high precision reflecting mirror switching device which is mounted coaxially with a primary mirror of a telescope system and arranged between the primary mirror and a secondary mirror. The high precision reflecting mirror switching device is characterized in that the switching device includes a follow-up type support mechanism, a space redundancy parallel drive mechanism and a rotation mechanism; and the space redundancy parallel drive mechanism achieves the turnover of a reflecting mirror to 90 or 45 degrees. When the reflecting mirror is turned to 90 degrees by the space redundancy parallel drive mechanism, the light reflected to the secondary mirror through the primary mirror is reflected by the secondary mirror to a Cassegrain focus; and when the reflecting mirror is turned to 45 degrees, the reflecting mirror reflects the secondary mirror light to an Nasmyth focus, and the rotation mechanism rotates to realize the switching of the Nasmyth focus. The invention solves the problems of mirror adjustment and focus switching of the reflecting mirror, the bearing capacity is strong, the mechanism has a configuration across space, the focus is quickly switched, the error of the reflecting mirror is dynamically compensated in real time, the reflecting mirror requires no additional stress adjustment, and the light is not occluded.