Abstract: The morphology characteristics of cownose ray is analyzed firstly and kinematic characteristics of cownose ray is observed as well as its kinematic model is set up.Then a new pectoral oscillation propulsion robotic fish named as"Cownose Ray-Ⅰ"is developed based on the principle of"likeness in shape".The robot fish is designed to be flat-shaped, consisting of two parts of main body and pectoral fins,without tail.The material of the main body is rigid while that of the triangular pectoral fins elastic.The chord of the robot fish whose total weight is 1 kg,its length is 300 mm,and its maximum span is 500 mm.The robot fish drives the rigid fin rays by eight eudipleural servo-motors according to certain phase difference,then 0.4 sine propulsion wave is achieved along the pectoral fins.Testing in the water tank,the robot fish gets forward velocity of 0.13 m/s and backward velocity of 0.15 m/s while left and right pectoral fins are moving in the same direction,and while both of the pectoral fins are moving reversely,the robot fish can turn 360°circling the origin point in about 8 seconds,presenting its excellent maneuverability.