The invention discloses a preparation method of health-care acerola cherry powder. The preparation method includes the following steps that 1, acerola cherries are dried and crushed, and the crushed acerola cherries are subjected to freeze drying for 1-5 hours at the temperature of minus 50-minus 100 DEG C; 2, the freeze-dried acerola cherries are mixed with preservative according to the mass ratio of 100: (0.01-0.1), and mixed powder is obtained; 3, the mixed powder is subjected to superfine grinding, and the health-care acerola cherry powder is obtained. The preparation method of the health-care acerola cherry powder is simple in process, and the prepared health-care acerola cherry powder has the effects of maintaining beauty and keeping young and enhancing body immunity and has a good health care function.