The study of the Mogao caves at Dunhuang has been done largely by the Dunhuang Institute, Wen-wu yan-jiu-suo, (abbreviated hereafter as Yan-jiu-suo). The majority of these caves have been dated by the Yan-jiu-suo. Many of the caves however are attributed only to 'Early Tang', 'Floruit Tang' or even vaguely as 'Tang'. The purpose of this thesis is to advance an alternative system of dating based upon the study of the decorative motifs and their schematic arrangement on the ceilings of the caves. But the present study does not aim at a complete survey of all the ceiling designs. Only those with marked changes in design are selected to provide a representative example of the chronology. The first chapter gives an account of the general history of the series of Mogao caves, known also as the Qin-fo-dong, or Caves of the Thousand Buddhas, and is followed by a review of current work on the subject. The second chapter groups the ceilings into two categories and gives a catalogue of the thirty-five selected ceiling designs. The third chapter consists studies of 3 major motifs in comparison with those appearing at other sites and on various artifacts. The fourth chapter deals with the schematic layout and the evolution of the ceiling designs. The fifth chapter points out particular caves where the accepted dating may call for revision, and gives a conclusion. Three circumstances affecting the history of the ceilings in general emerge from the study. The individual motifs are drawn not only from the religious repertory, but also from secular art of metropolitan China and thus reflect the inter- communication between the two areas. The ceiling designs as complete patterns were not however adopted in metropolitan China, and remained provincial, confined to North-west China. There is strong evidence suggesting the use of pattern books or stencils shared by painters when decorating the ceilings.