The invention discloses a high-frequency-vibration servo hydraulic cylinder. The servo hydraulic cylinder comprises a cylinder barrel; a left cylinder cover and a right cylinder cover which are identical are fixed on the left end surface and the right end surface of the cylinder barrel in a sealed manner; a piston rod is sleeved with the cylinder barrel; two ends of the piston rod penetrate through the left cylinder cover and the right cylinder cover and are fixed in the left cylinder cover and the right cylinder cover in a sealed manner; through holes are formed in the surface of the left cylinder cover and the surface of the right cylinder cover; the piston rod comprises a left piston rod, a piston and a right piston rod which are connected and fixed sequentially and are molded integrally; a piston seal is fixed on the outer surface of the side wall of the piston in a sleeving manner; the piston is in sealed connection with the inner surface of the side wall of the cylinder barrel bythe aid of the piston seal; and the outer surface of the side wall of the left piston rod and the outer surface of the side wall of the right piston rod are sleeved with metal supporting rings and piston rod seals. The hydraulic cylinder is quick in system response, good in dynamic characteristic and high in motion precision, low-amplitude and high-frequency vibration can be realized through cooperation of a servo valve group and a high-precision displacement sensor, and meanwhile, the amplitude can be adjusted as required.