The present invention relates to an oseltamivir phosphate granule and preparation method thereof. The said granule comprises 1.97-19.8 wt. % oseltamivir phosphate, 75.0-97.5 wt. % diluent, 0.1-5.0 wt. % binder, optionally 1.0-5.0 wt. % edible flavouring essence, sweetener and/or edible pigment. It is prepared by using 30-55 v/v % aqueous ethanol solution as moistening agent. The granules prepared by the formulation and method according to the present invention have good uniformity and stability and are water-soluble. The administration dosage of the granules can be conveniently selected based on the age and body weight of patients. The oseltamivir phosphate granule is suitable for administering to old people, children and flu gravis patients and those patients that swallow inconveniently or difficulty. The preparation of the granule is simple and low in production cost.