The invention belongs to the technical field of preparation of catalysts, and concretely relates to a 
porous carbon aerogel catalyst, and a preparation method and an application thereof. The method comprises the following steps: dissolving 
cellulose under a high-speed stirring condition, mixing the dissolved 
cellulose with a 
transition metal salt solution, and sequentially solidifying, 
drying, carbonizing and washing the obtained 
mixed solution to simultaneously achieve the preparation of 
aerogel and the loading of a 
transition metal in order to obtain the 
porous carbon aerogel with highly dispersed catalyst active sites. The catalyst has a good stability and a high catalytic activity, and can efficiently catalyze the 
transfer hydrogenation reaction of aldehydes, ketones or levulinates andalcoholic organic substances, wherein the conversion rate of aldehydes to alcohols reaches up to 98-100%, and the selectivity of alcohols reaches up to 81-99%. The catalyst is a 
solid aerogel 
monolith catalyst, so the catalyst can be well dispersed in a solution without stirring, and is easy to separate and recover. Additionally, the catalyst adopts 
cellulose as a 
raw material, so the catalyst has the advantages of low cost, greenness, 
environmental protection, renewability, simple preparation process, and easiness in industrialization.