The invention provides composite aluminum-based lubricating grease and a preparation method thereof. The composite aluminum-based lubricating grease is prepared form the following components based onthe total weight of the lubricating grease: a benzotriazole derivative, a composite aluminum-based thickener, a thioester type anti-oxidant and a main amount of lubricating base oil. The composite aluminum-based lubricating grease has a low friction coefficient, a high dropping point, good extreme pressure anti-wear performance, anti-corrosion performance and mechanical stability and excellent thermal stability, colloidal stability, oxidation resistance, anti-rust performance and water spraying resistance, and can be used for lubricating food machinery under harsh working conditions.