The work aims to expound the similarities and differences of pattern composition of traditional architectural carvings in Yangzhou and Suzhou and explore the corresponding causes. Based on a large number of wood carvings, stone carvings and brick carvings in the traditional architectures of Yangzhou and Suzhou, the pattern composition was analyzed with complex natural and story themes as the standard, and the plane composition, three-dimensional composition, design techniques, layout skills, compositional relationship and object expression were compared comprehensively in the traditional architectural carving patterns of Yangzhou and Suzhou. The pattern composition of traditional architectural carvings in Yangzhou and Suzhou presented various formal features according to different practical purposes, aesthetic requirements, subject matter content, as well as materials and craftsmanship. The pattern composition of traditional architectural carvings in Yangzhou and Suzhou evolves towards "planarization" and "three-dimensionalization" due to the effects of multiple regional factors. Yangzhou carvings mostly adopt head-up composition, which determines that Yangzhou carvings tend to be "planarization", while Suzhou carvings mostly adopt stereo composition, so the Suzhou carvings are developing towards "three-dimensionalization".