The invention discloses a medicine for assisting in treating acquired immune deficiency syndrome and a preparing method thereof. The preparing method includes the steps that 1, 20-30 parts by weight of raw radix astragalis, 15-20 parts by weight of burdock roots and 10-15 parts by weight of roots of soulie barberry are respectively taken, soaked, carefully selected, cleaned and dried, the burdock roots, the roots of soulie barberry and distilled water are weighed in the weight ratio of 200:50:1000 and jointly decocted for 1 h to 2 h, the decocting-extracted liquid medicine is filtered with a 50-70-mesh screen, and filtered liquid is obtained; 2, the filtered liquid obtained in the step 1 is concentrated to be 1.25 to 1.35 in relative density, and concentrated liquid is obtained; 3, 20-30 parts by weight of raw radix astragalis powder are added into the concentrated liquid obtained in the step 2, the mixture is mixed to be even, and the medicine for assisting in treating acquired immune deficiency syndrome is obtained. The medicine has obvious effects in the aspects of repairing CD4 cells of a patient, improving the immunity of the patient, improving disease resistance, prolonging the lifetime of the acquired immune deficiency syndrome patient, improving the living quality of the acquired immune deficiency syndrome patient and the like.