This paper studies new configuration and working principle for flow-mode dampers featuring magnetorheological fluid (MRF). Conventional designs usually employ magnetic coils to generate magnetic field for MRF activation, which leads to complicated structure and high cost of MRF dampers-based systems. In the new configuration, magnetic coils are replaced with permanent magnets distributed at the stroke ends. The higher the vibration, the more MRF is activated and the higher the damping force is produced. As a result, the damper can adapt itself to external excitations without any control. With compact and economical structure, the commercial ability of the product is significantly improved. To enhance performance, the geometric design of the proposed self-adaptive MRF damper is optimized based on finite element analysis (FEA), using Adaptive Single-Objective (ASO) algorithm in ANSYS optimization tool. The simulation results are then discussed and evaluated.