A comprehensive summary and comparison were carried out on the recently reported results given the types and properties of functional compounds in tomato skin, seed, and residues, as well as the suitable methods and techniques. The processing characteristics of the nutrients in tomato processing by-products were obtained in aspects of lycopene, dietary fiber, oil, and protein and the suitability, properties, advantages and disadvantages of different processing methods and technologies. The problems and the perspectives in the extensive use of tomato by-products were also proposed and discussed.