Steam blanching is needed to reduce the difficulty of peeling Citrus reticulata Blanco before peeling. Because the parameters of steam blanching depend mainly on experience, insufficient or excessive steaming often leads to poor peeling and damages quality of pulp. The heat transfer model of Citrus reticulata Blanco was established based on the finite element method. The variation law of the internal temperature field of citrus under steaming was studied. The steaming time of citrus with different fruit diameters was predicted. The results showed that the convection heat transfer between steam and the surface of citrus peel caused the temperature to increase sharply during steam blanching. The heat was transferred radially to the pulp center. With the extension of steaming time, citrus was heated more evenly along the radial direction, the surface temperature of pulp increased rapidly and then stabilized, and its heat transfer rate increased first and then decreased. The smaller the fruit diameter, the greater the heat transfer rate on the pulp surface, and the higher the pulp surface temperature at the same steaming time. In order to ensure that the quality of citrus pulp will not be damaged, the blanching time of citrus with small fruit diameter should be less than 77 s, and the blanching time of citrus with large fruit diameter should be less than 172 s. It will provide reference for optimizing steam blanched peeling process of Citrus reticulata Blanco.