Abstract: A high-temperature strain of green alga Scenedesmus obliquus selected by incu-bating the cells under the high temperature condition for a long period has beenobtained.The morphological and developmental changes of cells after a long periodof high temperature cultivation (36℃ in the dark period,42℃ in the light period)have been observed,and a synchronous culture has been obtained.The growth ofcells occurs under illumination and the cell division takes place in the dark.Twelvehours after the beginning of the light period,cells become ripening,and transforminto“mother cells”.The production of the autospores and the maximum autosporeliberation set in within four hours after the beginning of the dark period.Theaverage number of daughter cell produced is 8.7.The growth rate K is up to 2.07(log_e units per day) under unsaturated light intensity.This high-temperature strainis characterized by its rapid growth.