Ancient timber structure on a slope is an important part of ancient Chinese architecture. Due to the unequal height constraint at the bottom of columns, it is different from the ancient timber structure on a flat in the aspects of architecture layout, structure characteristics and seismic performance. In recent years, the investigations on seismic damage of ancient buildings show that the damage degree of ancient timber structure on a slope is generally more serious than that of ancient timber structure on a flat. To protect ancient timber structure on a slope much better, the basic concept of ancient timber structure on a slope is expounded and the architecture characteristics, structure forms and structure characteristics of ancient timber structure on a slope are summarized. According to the results of many investigations on seismic damage of ancient buildings, the typical earthquake damage characteristics and causes of ancient timber structure on a slope are analyzed, such as foundation failure, column foot slip, mortise-tenon failure, column frame torsion, roof failure and frame collapse. and the similarities and differences of seismic damage to the ancient timber structure on a flat are pointed out. The key scientific problems of seismic research on ancient timber structure on a slope are illustrated from the aspects of dynamic characteristics, seismic mechanism, failure mode and reinforcement method and the thinking and direction for the subsequent seismic performance research are pointed out.