| It was supposed to employ hydrostatic bearing technology for rocket thrust vector control system, to bring its load deflection resistance and low friction merits. However, the rockets always worked in serious conditions with much higher and larger span temperatures, causing the hydrostatic bearing full of gas and much compressible, which contributed to the piston rod response overshoot and vibration. If the overshoot was too large, the oil slick will broke and lost its radial force holding feature. The present paper work modeled the piston rod dynamic motions and obtained the system transfer function with equation part linearization, to conduct a detailed investigation of hydrostatic bearing dynamic behavior. It was found that, higher oil supply pressure assures higher radial force holding ability, but meanwhile the overshoot response would be more likely to occur. Reasonable bearing cavity depth would prevent the response overshoot and maintain the force holding ability. Moreover, a cone shape design of bearing cavity would reduce the leakage.