For the study of the Angkor period, the apex of Cambodian history, one of the most important historical sources is Notes on the Customs of Cambodia (Tchen la fong t'ou ki) by Chou Ta-kuan.In 1296-1297 Chou Ta-kuan accompanied a Chinese mission which stayed in Cambodia for nearly a year. After returning to China, Chou Ta-kuan wrote the above report. The description of the state of Cambodia in this report, in conjunction with epigraphic material, enables us to understand what the civilization of Angkor was like on the eve of its decline.In this article the author tries to find the original Cambodian (Khmer) words which are transcribed into Chinese by Chou Ta-kuan in the book cited above. In his study, he makes references to previous attempts by such scholars as P. Pelliot, G. Coedes and E. Aymonier.The most important results of this study are follows. Concerning local. names, Tch'a-nan is identified with the town of Kompong-Chnang, village of Buddha with Pursat, Mou-leang with Malyan in inscription (southern part of Battambang province) and P'ou-mai with Phimai.In term describing palace and officials, the word nan-p'ong is identified with nea-moun (Cambodian [=Camb.], officer), tch'en-kia-lan with (rea) chong-kea-reak (Camb, collaborator near the King), pa-ting with (Ka) mraten (Camb., a title), ngan-ting with (K) am(ra)-ten, ssen-la-ti with sresthin (Sanskrit [=Skt.] chief of Corporation), and mai-tsie with me-srok (Camb., village chief).Among the words concerning religion, pan-k'i is identified with pandita (Skt., great person), tch'ou-kou with chao-ku (Siamese, Budhist monk), pa-sseu-wei with tapasvin (Skt., ascetics who worship the linga) and Po-lai with prah (Skt., holy).As for language and writing, the word ngan-ting-pa-cha is identified with ât-deng-phea-sa (Camb., do not understand the language), pa-t'o with bei-da (Camb., father, appellation used by the princes), mi with me (Camb., mother), so with so (Camb., white), pou-sai with pe (Stieng, numeral) seh (Camb., horse).Concerning festivals, the word ya-lie is identified with rap riep (Camb., count) and ngai-lan with ram (Camb., dance).Among the words concerning ordinary daily life, pao-leng-kia is identified with ranko (Camb., rice), kiao with kajang (Malay, palmfrond roofing), sin-na with sam-pou (Camb., sailing vessel), p'i-lan with baloon (Mahr., boat), sen-mou with samnak (Camb., rest) and san-pa with sam-peah (Camb., salutation).Generalizing from his analysis, the author points out that the Cambodian language used at the end of the thirteenth century has a strong resemblance to that used at present.