The present invention is to prepare high quality blueberry leaf tea based on the fact that functional materials such as polyphenol, proanthocyanidin, tannin, chlorogenic acid, etc., are contained in blueberry leaves in abundance. Especially, the functional materials of the blueberry leaves are the highest at the end of October and November, so that the present invention prepares the blueberry leaf tea by using the blueberry leaves in this season. The tissues of the blueberry leaves are too thick and rough to squeeze the functional materials of the leaves by using the traditional tea preparation methods which collect, steam, and dry the leaves. Accordingly, the present invention processes the leaves through refrigeration, defrosting, compression, and expansion steps to soften the tissues of the blueberry leaves and widening the gross area of the blueberry leaves, so that a large amount of the functional materials can be easily and rapidly squeezed into the tea. The method for preparing blueberry leaf tea of the present invention uses the blueberry leaves whose growing period has been passed, and which are used to be wasted in farm families, thereby providing an additional income source, and not damaging the crops in the following year. To this end, the method for preparing blueberry leaf tea comprises the following steps: collecting blueberry leaves, washing the collected leaves, and making the leaves absorb water by soaking the leaves in water for two to three hours performing, one or more times, processes of defrosting after refrigerating the leaves whose moisture is removed placing the leaves in a pressure resistant container, seals the container, injecting compressed air into the container, and primarily applying pressure to the container secondarily applying the pressure to the container by heating the container from the outside thereof while vertically rotating the container and collecting the leaf tea by opening the container and rapidly expanding the blueberr
