The invention discloses an abalone shell pigment and a preparation method thereof. An abalone shell is adopted as a raw material, an algae pigment at the outer layer of the abalone shell is extracted by adopting an acid solution, and the abalone shell pigment is processed in decalcifying, purifying and precipitating manners. The abalone shell pigment has the characteristics of acid solubility, alkali insolubility, water insolubility and hydrophilic organic solvent insolubility. E490<1%>1cm of a blue-green pigment is greater than or equal to 75, E600<1%>1cm of a reddish-brown pigment is greater than or equal to 50, the calcium content is smaller than or equal to 2.5%, the total nitrogen is smaller than or equal to 7.5%, and the total sugar is smaller than or equal to 5.0%. The abalone shell pigment can be efficiently extracted under the conditions of room temperature, low acid concentration and short time, active ingredients of the abalone shell pigment are reserved to the maximal extent by the processing procedures of purifying, precipitating, washing, drying and the like; the abalone shell pigment is novel in conception, abundant in raw materials, high in production efficiency, low in preparation cost, simple in technology, green and environment-friendly, convenient to implement, and great in generalization performance, and a new path is found out for high-valued utilization of the abalone shell.