The invention discloses a porous carbon-loaded composite material catalyst as well as a preparation method and application thereof. The catalyst consists of a carrier, an active component and a carbon quantum dot, wherein the active component and the carbon quantum dot are loaded on the carrier; the size of the carbon quantum dot is not more than 10 nm; the carrier is porous activated carbon; the active component is one of or a combination of several of platinum, palladium, iridium, ruthenium and rhodium; based on the mass of the carrier, the loading quantity of various metals in the active component is shown as follows: the platinum is 0-10.0 percent by weight, the palladium is 0-10.0 percent by weight, the iridium is 0-10.0 percent by weight, the ruthenium is 0-10.0 percent by weight, and the rhodium is 0-5.0 percent by weight; the loading quantity of the platinum, the rhodium and the palladium is not 0; the total loading quantity of the active component is more than 0.5 percent by weight and is not more than 20 percent by weight; based on the mass of the carrier, the loading quantity of the carbon quantum dot is not more than 15.0 percent by weight. The invention further provides application of the porous carbon-loaded composite material catalyst to the reaction of synthesis of chloroaniline by selective catalytic hydrogenation of chloro-nitrobenzene. The catalyst has the characteristics of being high in conversion rate, high in catalytic activity and high in stability.