The invention discloses a preparation method of dietary fiber contained broken rice milk. A preparation process mainly comprises preparation of dietary fiber and preparation of rice milk, wherein wheat bran dietary fiber is prepared through procedures of puffing pretreatment by a twin-screw extruder, starch hydrolysis by amylase, protein hydrolysis by alkaline protease, bleaching, absolute ethyl alcohol precipitation, filtering, drying and the like; preparation of the dietary fiber contained broken rice milk mainly comprises steps of soaking and cooking of broken rice, grinding of cooked broken rice, peanuts or/and red dates, adding of white granulated sugar, xanthan gum and monostearin, blending, filling and ultrahigh pressure sterilization. Byproducts produced in rice and wheat processing industry are sufficiently utilized, and accordingly, broken rice and wheat bran are effectively utilized; a food additive, a stabilizer and a thickener can be reduced by means of the dietary fiber added to the rice milk, and besides, the rice milk has good physiological efficacy; through ultrahigh pressure sterilization, loss of nutritional ingredients and degradation of color, flavor and taste of the rice milk due to high temperature are reduced to the greatest extent.