To study the factors that influence the test precision of percent air voids of asphalt mixture based on mesoscopic scale, German Phoenix v|tome|x S240 industrial X-ray CT was utilized in combination with orthogonal test and variance analysis to study how different CT parameters and gradation types influenced the 3D reconstruction volume parameters of asphalt mixture. Marshall specimens were scanned by changing the parameters of CT and gradation types of asphalt mixture and the results were used for three-dimensional analysis, the relation between influence factors and percent air voids was also built, and then determine the optimal scanning parameters. The test results showed that it is feasible to make three-dimensional volume analysis of asphalt mixture on the basis of meso-scale; the scanning parameters and gradation types have different levels of effects on reconstruction results; the test accuracy would be improved by increasing scaning voltage and current properly and as well as choosing the appropriate filters. The percent air voids that obtained on the base of both meso-scale and macro-scale had good correlation under the condition of appropriate parameter of apparatus,in addition can improve the accuracy and economy of the test.