Taking Koi as the biological prototype, the structural design and optimization of fish like bionic flexible wing were carried out. The swimming posture of Koi was characterized by circulating pool experiment; Based on origami structure, the structure model of fish like bionic flexible wing is established, and the characteristics of driving load and vibration amplitude are studied. The orthogonal experiment is designed to analyze the influence of the main geometric parameters on the performance of the fish like bionic flexible wing, and the performance is further analyzed through periodic motion. The results show that the influences of the thickness of the outer plate, the thickness of the inner plate and the angle of the diaphragm on the driving load and vibration amplitude increase in turn. The thickness of bionic flexible wing outer / inner plate and baffle angle are 0.7mm/0.3mm and 75°. The maximum deviation between the swing posture and the actual swing posture of koi is 8.13%. And the ultimate yield range of the structure is far greater than the maximum yield range of the test, and the springback performance is good.