The invention relates to a separated drive spindle system of ultraprecision machining tool, relating to a ultraprecision gas static pressure spindle system. The invention is designed for solving the problem in the existing ultraprecision machining tool that an electric motor and the spindle of the spindle system are in rigid connection, power transmission effect is poor and the rigid connection affects gyration precision of the spindle. After being electrified, an AC servo motor starts to rotate and drives a flexible drive assembly to rotate; a flat belt rotates to drive a driving lever to produce torque to drive the spindle to rotate for carrying out cutting. High pressure air gets in through a radial air inlet hole, is throttled through a radial small throttling hole and forms a radial gas static pressure film at the gap of the radial gas film; the radial gas static pressure film supports the spindle and radial load thereof; high pressure air is throttled through a first axial smallthrottling hole and then forms an axial gas static pressure film at the gap of an axial gas film, the axial gas static pressure film supports the spindle and axial load thereof. The invention is applied to ultraprecision machining tools and milling machines with various forms.