A novel measurement system based on Hanning-window-changing density fringes and two-dimensional vision was proposed for monitoring the tank settlement. The artificial Hanning-window-changing density fringes were attached to the surface of the tested storage tank, and the surface fringes were collected in real time by a far-focus imaging camera at a certain distance, and then the images were processed by a specific image processing algorithm to extract the settlement displacement of the storage tank. The image sequences of tank settlement under different conditions were simulated by SOLIDWORKS 3D modeling, motion simulation and image imaging module, and the main measurement performance influencing factors, measurement feasibility and accuracy were simulated and analyzed. The simulated experimental measurement system of tank settlement was constructed, and its measurement performance was analyzed experimentally. The results show that the proposed system can realize real-time monitoring of the tank settlement displacement, and the measurement accuracy can be better than 10 μm at a distance of 7.5 m.