Through the investigation of the three marked relative clauses of zhi(之),suo(所)and zhe(者)in ancient Chinese,the study reveals that the frequency and function of the relational markers suo(所)and zhe(者)have changed significantly in Middle Chinese.These changes have typological significance.First,there was a shift in Middle Chinese from prioritizing subject extraction to prioritizing object extraction in marked relative clauses;Second,the marked relative clauses in Chinese have developed from being headless relative clauses in the pre-Qin period to becoming gradually headed relative clauses after the Han Dynasty.Finally,it briefly discusses the relationship between the development of marked relative clauses in Middle Chinese and the structural auxiliary word di(底)in Modern Chinese.