The present invention provides a banana peel pet dog food and a preparation method thereof, and belongs to the technical field of feed manufacturing. The dog food comprises the following components inparts by weight: 150 to 300 parts of banana peel, 50 to 100 parts of flour, 400 to 500 parts of rice, 150 to 200 parts of soybeans, 60 to 100 parts of dried fish fillet, 2 to 5 parts of salt, 10 to 20 parts of bone meal, 0.5 to 2 parts of composite vitamin, 0.2 to 2 parts of a trace element premix, 2 to 5 parts of yeast powder and 3 to 8 parts of spirulina. The banana peel is firstly subjected topretreatment, and the pretreatment process is as follows: subjecting the banana peel to dicing and pulping to obtain slurry, then adding candida utilis and extracellular tannase into the slurry for enzymolysis, and finally conducting drying. The banana peel pet dog food prepared by the method has balanced nutrition structure and good palatability, and causes no anorexia due to long-term consumption.