Aging of an asphalt binder causes the changes in the microstructure and, consequently, in the nanomechanical and rheological properties of the aged asphalt binder. Short-term aging on asphalt binders was simulated using rotating thin film oven (RTFO). These changes in the microstructure and nanomechanical and rheological properties were measured using atomic force microscope (AFM) and dynamic shear rheometer (DSR). The results indicated that (1) the adhesive force of the asphalt binder from AFM tests was increased after RTFO aging; (2) G* of the asphalt binder from DSR tests increased after RTFO aging; (3) the results from AFM were consistent with those from DSR, explaining the mechanism of the changes of rheological properties.