The invention provides a cinnamon oolong tea and a preparation method thereof. The preparation method comprises the following steps: A, preprocessing cinnamon, i.e. grinding dry cinnamon into cinnamon particles; B, picking fresh leaves of oolong tea; C, carrying sunning; D, carrying out cooling of green leaves; E, carrying out making of the green leaves; F, removing green; G, adding the cinnamon particles obtained in the step A into the oolong tea subjected to green removal, uniformly mixing and rolling to obtain a mixture, wherein the weight ratio of the addition quantity of the cinnamon particles to the quantity of the fresh leaves of oolong tea is (3 to 10):(360 to 390); H, drying to obtain the cinnamon oolong tea, wherein after drying, the weight ratio of the cinnamon to the oolong tea is (3 to 10):(90 to 97). The cinnamon oolong tea provided by the invention not only keeps the characteristics of natural flower fragrance, mellowness, refreshment and the like of the oolong tea, but also fuses aroma and taste of cinnamon, has more mellow taste and has unique flavor; due to adoption of a low-temperature and vacuum freeze drying mode, effective ingredients of the oolong tea and the cinnamon can be further kept and are beneficial to an effect of reducing blood sugar of the cinnamon oolong tea; the cinnamon oolong tea is suitable for wide population.