Abstract: Egg yolk has become a focus because of its abundant and special nutritional properties. Unsaturated fatty acid is highly focused by national researchers widely over the world because of its physiological function such as the prevention of diabetes, anti-inflammatory and antioxidant properties, and has been a hot spot in the field of food. This paper presented the developments of unsaturated fatty acid of egg yolks' physiological functions and explained that unsaturated fatty acid of egg yolk had many physiological functions such as the improvement of vision, protection of the sperm quality. Subsequently it can be widely used in the field of medical treatment, health care and food. Also this paper can provide references to the researchers in the relative fields.