Abstract: The far-infrared drying technical was used to red jujube mud on half-drying red jujube at this article.The water effective diffusion coefficient of the red jujube,dry activation energy and the changes of VCcontent was studied through the single factor experiment in different radiation temperature(55,60,65,70 and 75 ℃),slice thickness(2,4 and 6 mm) and radiation distance(80,110 and 140 mm) of the drying characteristics. The results showed that it had much significant impact of jujube infrared drying time and V_C content under the different radiation temperature(p<0.05),slice thickness and radiation distance. Under the test conditions,the influence of different factors on the drying time significant order:The radiation distance(p=0.001)>the piece of thick( p = 0. 002) > the temperature( p = 0. 003), and the influence of different factors on the V_C content in significant order:the temperature(p<0.001)>the radiation distance(p=0.001)>the piece of thick(p=0.032). The whole drying process of jujube sheet belonged to slow down drying. The water effective diffusion coefficient was 1.10674 ×10-10~9.67179 ×10^-10m²/s and the required drying activation energy was 53.79 k J/mol.Radiation temperature was the most important influence on jujube piece of V_C. It had fast drying speed and could keep the high content of V_C when the radiation temperature was 65 ℃,radiation distance was 110 mm,slice thickness was 4 mm.