To provide reference for gradation design of anti rutting skeleton dense structure asphalt mixture, the accurate calculation method of VCAmix which reflect the state of asphalt skeleton, and evaluation indexes of skeleton dense structure asphalt mixture were put forward based on digital image processing technique, meanwhile, the microscopic contact characteristics of coarse aggregate were also analyzed. The results indicate that surface air void and the number of contact point are inhomogeneously distributed along the depth of superpave gyratory compactor（SGC） specimen, in which larger surface air void and less contact points are at both ends of specimen, while smaller surface air void and more contact points in the middle of specimen. The VCAmix（IMAGE） calculation method considering coarse aggregate contact characteristics avoids the error of the empirical method. It is stricter, and more reasonable than the latter and can better ensure the formation of coarse aggregate skeleton. There is good correlation between VCAmix（IMAGE）, mean coordination number of coarse aggregate and rut depth, VCAmix（IMAGE）≤VCADRC and mean coordination number of coarse aggregate could be used as the main skeleton performance evaluation indexes of asphalt mixture.