The invention discloses relates to an automotive composite structural component and a preparation method thereof. The structural component comprises a nano-crystalline cellulose layer (1), an aerogellayer (2), a fiber cloth layer (3) and a resin layer (4), wherein the aerogel layer (2) covers the outer side of the nano-crystalline cellulose layer (1); the fiber cloth layer (3) covers the outer side of the aerogel layer (2); the resin layer (4) is subjected to compression molding on the outer side of the fiber cloth layer (3). The automotive composite structural component provided by the invention has the advantages of being lightweight, high in modulus and excellent in Impact resistance, is low in cost, and all materials can be recycled.