Aiming at the problem of uneven heating of longan, excessive microwave drying rate and local over-focus, the vacuum microwave drying was carried out by the combination of intermittent microwave and variable power microwave. In this paper,the changes of water ratio and drying rate in the vacuum microwave drying process were analyzed, such as the power density, vacuum degree and loading quantity. Seven thin layer fitting models were tested. The orthogonal experiment of three factors and three levels for color, total phenolic content and rehydration evaluation was established. The optimum intermittent vacuum microwave drying process of longan was optimized. The results showed that the effective diffusion coefficient of the longanpresented rising trend with increasing power density and vacuum degree, and with decreasing loading capacity. Among the seven mathematical models, Two-term model was the best fitting one. The optimized intermittent vacuum microwave drying process of longan was under the condition of a power density of 12 W/g, vacuum degree of 90 kPa and loading capacity of 100 g.