Abstract: One of the essential characteristics of flash butt welding is the discontinuity of the flash heating process caused by the contact bridges.If this characteristic is adopted as the principle of the platen movement control,the stability and the heating efficiency of flashing proceess Can be increased drastically.A closed loop electro-hydraulic servo control system has been designed and applied to a conventional general purpose welding machine.With this system the control of platen motion according to the instantaneous process of the individual contact bridges can be achieved.By means of instantaneous regulation of the platen movement the macro velocity of the moving platen can be self-adjusted to suit the changes of the melting speed of the workpieces and the required specific power can be reduced down to only one tenth of that with conventional predetermined platen movement control.