Reciprocating high speed wire-EDM tool was discussed in detail,including the importance of wire electrode tension constant and the influencing factors of wire electrode tension changes.Current tighting wire methods,namely manual wire,heavy hammer and spring loaded tension,were introduced while the advantages and disadvantages of these methods were analyzed.The design requirements for high speed wire-EDM tool tension control system were illustrated,the system needed to realtime adapt to wire electrode tension changes.Therefore the motor servo drive and electric hydraulic servo drive technology solutions were put forward,and the implementation of these two kinds of solution method and the technical problems needed to resolve were analyzed.