This equipment is used in double-sides grinding for semiconductor silicon wafers. 35 pieces of 8-inches silicon wafers or 15 pieces of 12-inches silicon wafers can be placed in one plate. With the hydrostatic rotary table, it is characterized with following advantages like strong bearing capacity, small power loss and long service life, etc.; in addition, its lubricating medium can play roles of vibration damping and error averaging with high precision and good precision assurance.