The invention discloses a compound haematococcus pluvialis astaxanthin fat emulsion preparation and a preparation method and application thereof. The fat emulsion preparation comprises haematococcus pluvialis astaxanthin, vegetable oil, an emulsifier, an antioxidant, a solubilizer, and an isotonic regulator. The preparation method comprises the following steps of: uniformly mixing the vegetable oil, the haematococcus pluvialis astaxanthin, partial of the emulsifier and antioxidant to obtain an oil phase; adding the solubilizer, the residual emulsifier, the isotonic regulator, a flavoring agent, essence and a preservative into water, and uniformly mixing to obtain a water phase; and adding the oil phase into the water phase, adjusting the pH value, adding water, homogenizing the obtained colostrum, filtering, filling nitrogen, and sterilizing to obtain the haematococcus pluvialis astaxanthin fat emulsion preparation. The fat emulsion preparation has high dispersibility and excellent storage stability, enhances the anti-fatigue capability and the learning and memory capability of aging model rats, improves the SOD activity in stomach tissues and reduces the MDA content, and has better effects of scavenging free radicals in vivo and resisting aging.