Abstract: Accumulated temperature is a basic specialized term in agrometeorology and other relative subjects which often occurs in papers of different journals. But there has been a big confusion of its scientificalness and unit for hundred years. Its origin,development,problem of scientificalness and improvement were reviewed in this paper. J.L.Monteith's theory was particularly introduced,in which the essential aspect of thermal time was discovered and explained. Paper titles with term of accumulated temperature and other terms with the same meaning i.e. thermal time,degree-day and heat unit in CAB Literature from 1990 to Oct. 2008 were retrieved. Results showed that there were less and less scientists using accumulated temperature,most using degree-day but more and more using thermal time. Considering the term of accumulated temperature had been using in China for dozens years and was very popular,in order to solve the problem of scientificalness and to keep agreed with physical principles,it was suggested to be replaced by "integrated temperature" ,which had the same Chinese characters and pronunciation,and the unit of "℃" should be also replaced by "℃·d". At the same time,the term explanation of "heat resource" in revised edition of Chinese Agronomic Terms(1993)was renewed as the following:a type of climatic resource different with heat energy in physics,i.e. combination of usable temperature conditions in agriculture and its continued time,usually expressed as integration of temperature to time.

Key words: Accumulated temperature and its unit, Accumulated temperature and its unit, Scientificalness, Thermal time, Degree-day, Heat unit