The Theory of Generalized Functions is the first monograph on generalized functions. This book is divided into nine chapters. The book systematically summarizes and highly summarizes the main works of L Schwartz, the author who won the Fields Prize that year. This paper discusses various basic properties, operations and transformations of generalized functions, and especially expounds that the famous Dirac function is actually a measure rather than a function. Thus, it lays a solid mathematical foundation for the wide application of Dirac measure in quantum mechanics and other disciplines.