Abstract: The Bell and Drum Towers of Buddhist temples in the Ming and Qing dynasties were mainly of square plan, while those of Ciyun Temple in Datong, Shanxi adopted a relatively rare circular plan. Based on 3D laser scanning and component surveying, this paper analyzes their design thinking from three aspects: dimensional design of the circular plan, adaptive measures of wooden components, and collaborative adjustment of the multiple trades in building the temple. It shows that local craftsmen in Ming dynasty adopted a “square-round transformation” mechanism, where the dimensions and positioning of key components such as column grids and oblique beams were determined by the geometric method of “scaling according to the square-diagonal ratio and rotating to obtain orthogonal-axis alignment”.