Speed, agility, maneuverability, range and efficiency of birds and insects are far beyond the conventional flying mini vehicles. There are various research works to create vehicles that imitate these amazing creatures. In this paper, a wing mechanism is designed for a micro aerial vehicle using four flapping wings. In this system, a four-bar mechanism is preferred as the wing mechanism. In order to obtain flapping motion from rotation of the motor, a crank rocker mechanism is used by connecting the shortest link to the fixed link. Flapping range ( swing angle) is determined by obtaining dead-center positions. It is chosen as large as possible since it is related to the lift force. Optimization of transmission angle is made in order to transmit torque from the input link to the output link with a minimum loss. The link length ratio is computed by deciding swing angle and angle between dead center positions. While computing the ratio of lengths of the links, deviation of transmission angle from 90 degrees is attempted to be adjusted to a minimum level. The dimensions of the wings are determined with respect to the lift force. The prototype vehicle has been designed and manufactured with the obtained results.