Abstract: The analysis and calculation of static characteristic were carried out for servo-tube guided hydraulic control rod driving mechanism. The static holding flow rate and its variation law with temperature were acquired. The results indicate that the static holding flow rate needed is very small in steady working range of variable throttle orifice. The liquid density decreases with the increase of temperature, and then the static holding flow rate increases accordingly. In inclining condition, the range of static holding flow rate is augmented and the holding characteristic of control rod is more stable. Therefore, the resistance ability to perturbation is much stronger and is conformable to the criterion of nautical nuclear power device.