The cause of using hydrostatic guideway in large floor type boring and milling machine was analyzed. The classification and characteristics of hydrostatic guideway were introduced, and also the parameters of ram hydrostatic guideway were calculated. Through the application of technology of hydrostatic guideway in large floor type boring and milling machine, the dynamic characteristics of the machine was good, and it also had the strong vibration resistance and high motion precision. The processing precision of the workpiece is improved greatly.