This paper presents a prototype of a flapping wing robot with a 24cm wingspan, a 20cm long body and a weight of 12.8g without battery and electronics. The prototype is composed of a driving mechanism, two pairs of wings, and a tail. The driving mechanism is simple but efficient, which is composed of a DC motor, a gear reduction unit and two pairs of crank-link mechanisms. The kinematics of the driving mechanism is analyzed. The simulation results show that the prototype can flap completely symmetrically with periodic angular velocity and angular acceleration as well as a flapping angle ranging from 23º to 90º. The experimental results show that the prototype can generate a flapping frequency of 12Hz and a lift force of 13g under the voltage of a lithium battery.