Abstract: Abstract: Grapes as a seasonal fruit, have relatively high sugar content and moisture content, and are very sensitive to microbial spoilage during storage. Therefore, grapes once harvested must be consumed or processed into various products within a few weeks in order to reduce economic losses. Drying grapes into raisins is the major processing method in almost all countries where grapes are grown. The knowledge of the drying mechanism is very necessary for heat and moisture transportation efficiency, energy savings and product quality. Several different empirical and semi-empirical drying models were used for describing and predicting drying curves. Some of these models could give a good fit to the drying curves, but the basic idea of process characterization was to consider the process as a ''black box''--the drying materials and drying conditions were difficult to be related to the parameters of these models used. In this study, the Weibull distribution model was applied to the drying process under different drying methods (hot air drying, pulsed vacuum drying), drying temperature (50、55、60和65 oC) and blanching pretreatment time (0、30、60、90、120 s). The result demonstrated that the Weibull distribution model could well describe the drying curves, for the moisture ratio vs. drying time profiled of the model showed high correlation coefficient (R2=0.993-1.000), and low root mean squared error (RMSE=2.72×10-3-2.12×10-2) and chi-squared (χ2=8.13×10-6-4.27×10-4). For the drying process, the scale parameter (α) defined the rate constant and represented the time needed to accomplish approximately 63% of the process. It was found that the scale parameter (α) was depending on the drying temperature and the drying method. When the drying temperature increased from 50 to 65 oC, the scale parameter (α) decreased from 2738.946 to 840.846 min for hot air drying and decreased from 813.219 to 294.831 min for pulsed vacuum drying, respectively. The blanching time could also affect the scale parameter (α), the value of α was decreased from 840.846 to 133.754 with the blanching time increased from 0 s to 120 s at drying temperature of 65oC. The shape parameter (β) was related to rate of the mass transfer at the beginning of drying. In this study, it was found that the shape parameter (β) was depending on the drying method and materials status. For the same drying method, drying temperature had little impact on the shape parameter (β=1.214-1.258 for hot air drying, 1.393-1.409 for pulsed vacuum drying). One important application of the Weibull distribution model is to determine the moisture diffusion coefficient (Dcal), whether the whole drying occurs in the falling rate period or not, by the scale parameter (α). So the Dcal of the grape samples were calculated, ranging from 0.2982×10-9 to 2.7700×10-9 m2·s-1, and it was found that increasing drying temperature, increasing blanching treatment time could enhance the Dcal of grape samples. The activation energy for moisture diffusion of grape samples was 72.87 and 61.43 kJ/mol by hot air drying and pulsed vacuum drying, respectively. It was demonstrated that drying method can affect the activation energy, and drying grapes with pulsed vacuum could save energy and increase efficiency. The result will provide a reference for the application of Weibull distribution on grape drying.