In order to accelerate the internationalization of Chinese agriculture after entry into WTO,and to introduce the productive technique of two-line hybrid rice initially invented in China to the world,on the basis of the temperature data of daily four times observations from 1980 to 1997 in Bangkok and Chiang Mai,Tailand,we supplement the missing observations with NCEP/NCAR re-analysis temperature statistics.In terms of calculations of theoretical daylength and fertility conversion index as well as developmental model of Pei’ai 64S,we analyze the climatic adaptability of fertility of photo-thermo-sensitivity male infertility Pei’ai 64S,which is planted most widely in China at present,in Bangkok and Chiang Mai-representative areas of rice production in Tailand,and give the earliest and latest sowing date of safe seed production under the assurance of 90,95 and 100 percent respectively,thus offering a realiable agroclimatic basis for the extention and application of two-line hybird rich technique in Tailand.