The invention discloses a special heat-pipe thermostatic bath. The thermostatic bath comprises a heat pipe, wherein a cylinder is arranged between an inner wall of the heat pipe and a sensor insertion pipe; the lower end of the cylinder is provided with a liquid channel through which a liquid-phase working medium circulates; and the upper end of the cylinder is provided with a gas channel through which a gas working medium can smoothly circulate. The thermostatic bath is mainly used for calibrating an oil level temperature controller for a transformer, a winding temperature controller for the transformer and other temperature controllers with electric output joints. On the basis that the indexes of the operating temperature range, thermostatic performance and the like meet the temperature controller calibration requirements, the thermostatic bath has the functions of rapidly raising and reducing the temperature, and the absolute value of the temperature raising and reducing rate r can reach 1 DEG C per minute.