As one of the most important components of a flapping-wing micro air vehicle (FWMAV), the design of an energy-efficient flapping-wing has been a research interest recently. Research on insect flight from different perspectives has been carried out, mainly with regard to wing morphology, flapping kinematics, and unsteady aerodynamics. However, the link between the wing morphology and kinematics with passive pitching has been neglected in flapping-wing design. To address this, a model based on a quasi-steady aerodynamic model and the passive pitching motion was made. To simplify the model and make optimization more feasible, the wing is modeled as a stiff plate with uniform mass distribution and a torsional spring at the wing root. An optimization is conducted with the objective of minimizing power consumption for hovering flight using the six most influential wing morphological and kinematic parameters as design variables. The sensitivity of lift generation and power consumption to all the parameters is analyzed. Compared to traditional artificial wings with straight leading edges as pitching axis, wings with a part of wing area in front of the pitching axis and smaller aspect ratio are able to perform more energy-efficient hovering flights. Preliminary design suggestions regarding the selection of wing shape and kinematics for FWMAVs are given.