The α-particles effects on the functions of phagocytosis and receptor Fc of macrophage were studied, in which α-irradiation was emitted from ,238,Pu source and macrophage like cell line P 388 D,1, were tested. Difference of sensitivities between phagocytosis and receptor Fc to α-irradiation was analysed. The changes differed with different durations of post-irradiation and doses of α-irradiation. Phagocytic function was enhanced during early period of post-radiation by low dose irradiation. Phagocytic function decreased certainly under large doses and/or long duration of post-irradiation. Relationship between doses and effects on suppression of phagocytosis was definite, which was a model of single decrease and suited to formula of minus exponent. Trend of suppressive changes both phagocytosis and receptor Fc was compared. The result indicated that the decrease of phagocytosis with increase of doses was faster than that of receptor Fc. It was suggested that phagocytosis was more sensitive to α-irradiation than function of receptor Fc.