The best proportion of potato and rice was obtained by different proportion ratio. Thereafter, different amounts of soybean, mung bean and millet were added to determine their viscosity value, and the addition amount of each single factor was screened by combining with sensory score. The optimal formula of potato compound rice flour was determined by mixing design, and in vitro simulated digestion experiments were carried out on the potato compound rice flour prepared by combining the physiological characteristics of middle-aged and elderly. The results showed that the best formula of potato with rice flour consisted of 12.31% soybean, 20.84% mung bean, 24.36% millet, 14.88% potato, and 27.61% rice. The starch digestibility is 82.48%, meeting the basic nutritional needs of the elderly.