The vision driving the work reported herein is to investigate the fluid-structure interac- tion (FSI) effects of the flexible laminated blades for tilt-body micro-air-vehicles (MAV) proprotors in hover and forward flight configurations. This is in order to exploit the po- tential of flexible-bladed proprotor over the rigid-bladed proprotor in the enhancement of proprotor performance during hovering and cruising at a target forward speed. For that, the FSI model taking into account the specific problems devoted to MAV-sized proprotor made of laminate composite was developed. The FSI model combines aerody- namic model adapting Blade Element Momentum (BEM) theory and structural model adapting Anisotropic Finite Element Beam (AFEM) theory. The aerodynamic model is developed to be capable of adapting in the analysis on low Reynolds number proprotors. In the structural model, the blade is modeled as an elastic beam undergoing deflections in flap, lag, and torsion to capture the coupling effects in anisotropic materials, adapts the structural analysis on proprotor blades made of laminate composite. The reliability of the developed FSI model is verified through a validation on both aerodynamic and structural models, separately, on several MAV-sized proprotors. As for a direction to the analysis on passively-adaptive proprotor blades, an optimal design on actively-adaptive proprotor was carried out. For this, a program for designing the optimum rigid blades at single-point (for either isolated cruise-point or isolated hover-point) and multiple-point (combined cruise and hover point) for proprotors have been developed. The procedures in the optimal design program employs the numerical iterative inverse design method, based upon the minimum thrust induced losses (MIL). Even if the work in this thesis was directed primarily towards the proprotor, however, the propulsion system from the motor part was not neglected since the propulsion efficiency is a crucial factor to the suc- cess of MAVs. A cheap and time-effective method of proposing the best motor from the selected commercial motors was developed, based on Taguchi’s method. The sensitivity of the total power consumption to the variation of value of each motor design variables was also studied. The benefit of the use of tip body in the blade and the effect of bending on the induced twist and on the thrust degradation, respectively, were also analyzed and identified. Finally, the systematically designed passively-adaptive composite proprotors were evaluated under steady operating conditions. Hovering and cruise propulsive performance, characterized by total power Ptotal, were compared between the rigid-bladed and flexible-bladed proprotors. As a result of the comparison, the flexible-bladed proprotor with fixed system is found to be capable of slightly enhancing the performance through the reduction in Ptotal over its optimal rigid-bladed proprotor.