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With the improvement of people’s living standard, people are more and more concerned about the quality of fruits and vegetables during freezing and cold storage. However, fruits and vegetables are constant in the process of freezing-thawing during freezing and cold storage. Therefore, it is very important to research the phase transition of fruits and vegetables during the freezing-thawing process. The phase transition of fruits and vegetables in the freezing-thawing process was studied by using red grape as the test object. Grape pulp was tested with different rates, frequencies, time intervals, rate gradients and the rates through maximum ice crystal generation zone during the freezing-thawing process by DSC. By analyzing the heat flow curve in the experiment, the effect of freezing-thawing process on grape sample under different conditions was found. The greater the freezing rate was, the lower the freezing point temperature was, the shorter the time during the freezing process was. With the increase of the rate, the peak temperature of phase transition, the end point of phase transition temperature and the latent heat of phase change all increased during the process of thawing. In the process of temperature change from 2℃/min to 20℃/min, the latent heat of phase change increased 1.79 times, the peak temperature of phase transition increased 0.94 times, and the end point of phase transition temperature increased 5.07 times. The study provides a basis of quality recovery after freezing-thawing process for fruits and vegetables.