Abstract: The direct drive hydrostatic rotary table concentrates many heat sources such as from motor heating, bearing friction and so on in limited space. As a result its strategy of thermal characteristics control and optimization seems particularly important. For a high-power and ultra-precision hydrostatic rotary table, the control strategy of itsthermal characteristics is studied from three aspects, including strengthening heat dissipation, reducing heat source intensity and structural optimization. Thanks to some technical measures such as hydrostatic support from large flow of thin oil, thrust upper and motor lower and forced cooling of motor, the thermal characteristics analysis and test indicate that the working end of the rotary table haslower temperature rise and smallerthermal elongation. Moreover the variations from hydrostatics-oil viscosity and oil-film gap caused by temperature rise and thermal deformation have little effect on the loading performance of the rotary table system. As a result the developed rotary system has excellent thermal characteristics.