The invention provides a composition for increasing immunity and its preparation method, which contains the following active ingredients by weight of 100 to 350 parts of protein, 10 to 300 parts of yeast glucan and 5 to 100 parts of haematococcus pluvialis. The composition used for enhancing the immunity has the beneficial effects that, body immunity can be enhanced though cooperated synergy effect of the raw materials, and the fatigue can be alleviated, thereby the composition is suitable for office workers.