B Vitamins are relatively deficient in food and loss vulnerably， they are nutrients that the human body cannot synthesize. Microcapsule embedding technology was used in this experiment， niacinamide， folic acid， vitamin B1 and vitamin B2 what is ingredients specified in the‘7+1’ fortified flour as core materiasl， gelatin and sodium carboxymethyl cellulose（CMC） as wall materials， mixed B vitamins microcapsules were prepared by vacuum freeze-drying. The embedding rate was determined by HPLC. The optimal technological conditions for the preparation of mixed B vitamins microcapsules were obtained by establishing a quadratic regression equation model by single factor test and response surface method： the concentration of wall material is 2%， the proportion of core wall is 2.41， proportion of wall is 1.75 ∶ 1， the embedding rate of microcapsule was 88.81%. Scanning electron microscope results show that spray drying has better uniformity and integrity than vacuum freeze drying， but the sum and adhesion of surface are more serious. The experimental results of slow-release kinetics show that microcapsules have certain slow-release effects on vitamins， the rate of release in gastric juice is less than that in intestinal juice， and they all follow the first-order kinetic model， so the water-soluble microcapsules with stable porous mechanism have been formed.