本文以山西芮城永乐宫的元代天花、藻井为主要研究对象，永乐宫天花、藻井是典型的元代官式小木作精品。研究一方面能够揭示元代小木作装修的在木构建筑中的作用及工艺特点，另一方面也可以更全面地反映小木作形制特点由宋金时期向明清转变的过程。本文使用精细测绘与现场手工测量相结合的方式获取详尽的基础数据，使用类型学和比较研究的方法对永乐宫小木作进行定位，通过文献整理及数据分析的方法进行形制、结构、尺度的研究。关于永乐宫小木作本体的研究主要包含两个部分：一方面结合不同时期的官式实例，对研究对象的形制特点进行研究分析，包括研究对象的结构逻辑、平面形制、斗栱形制、空间关系、文化寓意等方面内容。第二方面结合精细测绘的方法，比照《营造法式》、《工程做法》等典籍，对研究对象的尺度设计规律进行探求，包括营造尺复原推算、斗栱用材分析、设计方法推测等内容。本文通过形制、结构和尺度三方面的研究，对永乐宫小木作的制度特点、设计规律进行全面的理解，从而认识元代小木作在宋式转向明清的时间脉络上的意义，以及其与建筑大木结构的关系。论文还对小木作天花、藻井实例进行梳理，通过对文献记载、石窟墓葬等仿木结构藻井、木构藻井实例、以及《营造法式》等建筑文法资料的解读、梳理，更加清晰的认识天花、藻井的功能、意义、类型、源流等问题，并尝试梳理藻井的发展演变体系。在此基础上，本文将其他实例与永乐宫的天花、藻井进行比较研究，来分析永乐宫天花、藻井的形制特点及价值定位。

This dissertation focuses on the ceilings and caissons of Yuan Dynasty in the Yongle Taoist Temple, whose “minor carpentry” of are typical official structures of superior quality. Not only does this research reveal the function and technics of interior decoration in wooden structures, but also it describes the transition of interior decoration from Song Dynasty to the Ming and Qing Dynasty. In this dissertation, manual surveying and 3D-lazer scanning methods are combined to obtain the required data for research, typology and comparative study is used to ascertain the outstanding universal value of interior decoration in Yongle Temple, methods of literature research and data analysis are also applied to figure out the types and scaling rules.The research on the ceilings and caissons in Yongle Temple, which is the core of this dissertation, can be divided into two parts. First, analysis of typology and structure. Studies of the form, the Dougong, space and connotation are included in this part. Second, exploration of scaling and designing rules, in which the standard ruler, the section of Dougong and the graphic designing are inferred. By the study of typology, construction and dimension of Yongle Temple, we are able to define the interior decoration of Yuan Dynasty as an inheritor and turning point in the process of evolution and to define the relationship between “major carpentry” and “minor carpentry” in Yuan Dynasty.This dissertation tries also to recognize the function, meaning, origin and types of ceilings and caissons in China, and to form the system of evolution of caissons, by summarizing the relative examples of ceilings and caissons including the description in documents, imitation of wooden structure in grottoes and tombs, caissons in wooden remains, as well as the building standards of caisson in YingZaoFaShi. On the base of these related studies, this dissertation also compares the ceilings and caissons of Yongle Temple with other cases to analyze their special features and value in the history.