Moisture damage has become one of serious distresses to reduce stability of pavement structure and service life. One of the most essential reasons for moisture damage is insufficient adhesion between asphalt and aggregate. Most conventional methods for evaluating adhesive characteristic are subjective and empirical and adhesion results are seriously affected by tester's operation habit and judgment. Meanwhile, active adhesion mechanism was not considered in most conventional methods. This study designed an active adhesion based test method, named active adhesion evaluation method (AAEM), to make up for the lack of research on active adhesion and eliminate the subjective operation in boiling process. Boiling water test was performed on basalt and steel slag aggregates for comparison with AAEM. Digital image processing was used for quantitative detection of adhesive characteristic. Results show that digital image processing can accurately and effectively measure asphalt coating ratio. Mixing time of 90 s, and asphalt content of 2.5% were finally selected as the optimum AAEM test parameters. The variance and standard deviation of coating ratios of AAEM are much smaller than that of boiling water, whether it is steel slag or basalt, indicating that the AAEM is indeed an effective method for measuring coating ratios of aggregates. The distinction of coating ratios for basalt and steel slag can be amplified by AAEM compared with boiling method.