Atomic force microscopy (AFM) is a powerful measurement tool, widely used in microfabricated structure inspection. However, since it is typical that the fixed tilting angle of a probe is employed in traditional AFM, the corner and sidewall image of the scanned sample would be distorted. To overcome the problem, a so-called adaptive tilting angle algorithm (ATAA) applied to a self-designed dual-probe AFM system is presented to achieve on-line sidewall estimation during scanning of general samples. Through the use of the proposed ATAA, the tilting angles of dual probes for each scan line can be self-adjusted to the optimal ones. Overall, a probe tilt mechanism is designed, which allows the AFM system to change the tilting angles of the probes during the scanning process such that the dual-probe structure AFM can acquire a complete high precision image with just a single scan. The experimental results show the performance of sidewall measurement and the high-precision image obtained by the proposed method.