Objective: This study aimed to obtain the temperature distribution law of different points in citrus fruit over time during heat treatment. Methods: The temperature change of citrus peel during heat treatment was studied from the perspective of heat transfer. A new method was applied to calculate the temperature transfer rule in citrus peel, and a new mathematical model was established to simulate the temperature distribution of citrus peel during heat treatment. The spatial and temporal distribution of the internal temperature field of three kinds of citrus (Fengjie Navel orange, longevity blood orange and Ziyang Tangerine) was studied. Results: The study showed that the heat treatment time decreased exponentially with the increase of water temperature, the detailed exponential relationship expression of different varieties of citrus was obtained, and the function formula between the heat treatment time and water bath temperature was proposed by the data regression method. Conclusion: Heat treatment time decreases exponentially with the increase of water bath temperature. Due to an insufficient heat transfer temperature differential, too low water temperatures will significantly lengthen the time needed for heat treatment and increase energy usage.