Historical comparative linguistics is a kind of historical linguistics that studies whether there is a genetic relationship between languages and their evolution process. Evolution and direction. The research method it uses is the historical comparison method. It compares the differences between languages or dialects, identifies cognate words through the law of phonetic correspondence, reconstructs the phonology of the original language, and finds out the evolution law from the original language to the languages of later generations.
The first chapter describes the materials and methods needed for Sino-Tibetan homologous historical comparison, and introduces the research results and difficulties encountered in Sino-Tibetan comparison in the past 50 years. The second chapter first introduces different views on the division of Sino-Tibetan language families and introduces the views of many scholars on the nature of primitive Sino-Tibetan language, and then tries to use Chinese written documents to verify the results of phonetics and loanword pairs in the Zhou, Qin and Han dynasties. The third chapter starts from the historical background of primitive Sino-Tibetan. This paper mainly uses the principle that loan words cannot form a neat phonetic correspondence rule in the loaned languages to distinguish the difference between cognate words and loan words between Chinese and Tibetan languages. Example operations are used to identify Chinese-Tibetan cognates and loanwords. Those that conform to this identification principle are all loanwords. After discussing the linguistic phenomena of Sino-Tibetan languages from various aspects, six principles are put forward on identifying Sino-Tibetan cognates and loanwords. The fourth chapter searches for Sino-Tibetan cognates through Sino-Tibetan comparison, and finds 22 Sino-Tibetan cognates through historical comparison of 1074 comparative terms. The fifth chapter compares the forms of the Tibeto-Burman language historically, and concludes that the Tibetan-Burman language can be traced back to the primitive Tibeto-Burman period with only three forms: dynamic, noun prefixes of limbs and animals, and antonym prefixes, and then compared with the forms of ancient Chinese.