The invention relates to a preparation method of rice flour with the low strip breaking rate. The technological process of the preparation method comprises the steps of rice cleaning, soaking, grinding into thick liquid, adding chitosan and protein, adjusting the water content, steaming, flour mixing, extrusion molding, aging, re-steaming, cooling and product finishing. According to the preparation method, a chitosan and protein composite system is added in the preparation process of the rice flour, the chitosan and corn starch are fully mixed first then to be added to rice milk, and the problems of uneven dispersion and easy caking of the chitosan added to the rice milk are solved; and at the same time, due to cross-linking between chitosan molecules with hydrogen bonds of the chitosan molecules into a net structure, entanglement is high, a chitosan solution has a certain viscosity, when added to the rice flour, the chitosan solution can improve toughness of the rice flour, the stripbreaking rate is reduced, the cooking loss of the rice flour can be reduced, at the same time, the shelf life of the rice flour can be prolonged, and nutritional value of the rich flour is improved.