The paper discusses what is formal beauty and the relationship between formal beauty and architecture. Comparing the viewpoints of Hegel and Engels, it is believed that architectural art is a kind of symbolic art, and the relationship between form and content is diverse and complex, so it is unnecessary to unify. The fundamental problem of non-pure art, including architecture, is its form and function. The formal beauty of the architectural is restricted by the necessary rules of architecture itself, and there is no universally applicable architectural theory. The accumulation, classification, and standardization of people’s long-term life have formed the rule of formal beauty. The fundamental principles of architectural form beauty are “diversity and unity” and “harmony”. In the process of modernization transformation, the phenomenon of evolution of “normal-abnormal-supernormal” appears in architectural aesthetics. The current Chinese architecture was born in both local and foreign factors, and has internalized the foreign factors to form a modern architecture with Chinese characteristics by way of this cross-culturalization.