In order to produce high quality concentrated watermelon juice, three batches of concentrated watermelon juice were obtained from the vacuum concentration. The results indicated that the total soluble solid contents of three concentrates were 37.5, 45.4 and 60.0 °Brix, respectively. The volume concentration ratio (VCR) are 4.26, 5.04 and 7.40, respectively. The concentrated watermelon juice, which has the VCR equal to 5.04, showed the best concentrated operation among those three batches of concentrated watermelon juice, which has the finest outlook, low viscosity, easy to flow, no local scorching characteristics. The turbidity of the concentrated watermelon juice shows a linear inverse ratio relationship with the time of concentration, it indicates that the heating in the concentration procedure can improve the layer separation of watermelon juice.