The present invention relates to a method for preparation of plant extract powder and oral compositions containing plant extract powder prepared by the same. More particularly, the present invention could provide a method for preparation of plant extract powder comprising the steps of (a) loading a plant extract having activities of prevention of and treatment for periodontal diseases or tooth decay into a porous powder carrier; (b) coating said carrier's surface with a water-insoluble coating agent and oral compositions containing plant extract powder prepared by the above described method which have an excellent periodontal diseases preventing effect and tooth decay preventing effect.