The present invention relates to a method for preparing a knitting yarn having a water repellent function. The present invention relates to the method for preparing a knitting yarn having a water repellent function, comprising the steps of: providing a knitting yarn in the form of a skein or a cone; carrying out washing in order to remove impurities and oils from the provided yarn; coating with water repellent by spraying a water repellent solution containing the water repellent at the washed yarn under pressurized conditions; dehydrating the water repellency-treated yarn, and then drying the same; and fixing the water repellent to the yarn by applying heat to the dried yarn.