The utility model relates to an improved electro hydraulic servo valve, which aims at solving the disadvantages of big hysteresis and small structural stiffness of a baffle and the like existing in prior electro hydraulic servo valves, and provides a novel jet nozzle baffle type servo valve, which comprises a jet nozzle 2,7, a slide valve 11 and a filter tube 10 are communicated through a fluid path channel system and arranged in a base 5 and a valve body 9, and is characterized in that a baffle 3,14 fixedly connected with a piezoelectric stack 4,12 is arranged on an outlet which is corresponding to the jet nozzle 2,7, and increasing or decreasing of a gap between the baffle and the jet nozzle is capable of being achieved through expansion of the piezoelectric stack.