An anesthetic vaporizer and a temperature compensation unit are disclosed. The temperature compensation unit, which cooperates with a vaporizing chamber having a bottom wall, includes a first device connected to the bottom wall of the vaporizing chamber for contacting with liquid anesthetic agent in the vaporizing chamber and changing in length according to temperature change of the liquid anesthetic agent, and a second device connected to the vaporizing chamber. A gas flow gap through which a gas flow passes is formed between the first and second devices. The gas flow gap becomes larger as temperature of the liquid anesthetic agent rises and smaller as the temperature of the liquid anesthetic agent drops. Since the first device is connected with the bottom wall of the vaporizing chamber, the first device will directly contact with the liquid anesthetic agent regardless of the liquid level of the anesthetic agent, as long as there is liquid agent in the vaporizing chamber therefore the efficiency of heat exchange is high and the effect of temperature compensation is good.
