Abstract: The present paper breifiy reviews the history of the classification of the living cycads, and emphasizes to introduce Stevenson's system of cycads. In former times, all the extant genera of cycads were classified in the one family Cycadaceae (Persoon, 1807). However, in 1959, L. A. S. Johnson showed that three distinct cycad groups were better accomodated in separate families. More recently, Dennis Wm. Stevenson (1990, 1992) has carried out a series of cladistic analysis on the living cycads. He proposed a classification system of the cycads based on a cladistic analysis of fifty-two characters ranging from gross morphology to phytochemistry. Stevenson' system of the extant cycads is as follows： Order Cycadales Subord. 1. Cycadineae Fam. 1. Cycadaceae Only genus Cycas Subord. 2. Zamiineae Fam. 2. Stangeriaceae Subfam. 1. Stangerioideae Only genus Stangeria Subfam. 2. Bowenioideae Only genus Bowenia Fam. 3. Zamiaceae Subfam. 3. Encephalartoideae Trib. 1. Diooneae Only genus Dioon Trib. 2. Encephalarteae Subtrib. 1. Encephalartinae Only genus Encephalartos Subtrib. 2. Macrozamiinae Macrozamia , Lepidozamia Subfam. 4. Zamioideae Trib. 3. Ceratozamieae Only genus Ceratozamia Trib. 4. Zamieae Subtrib. 1. Microcycainae Only genus Microcycas Subtrib. 2. Zamiinae Zamia, Chigua The author agrees with D. Stevenson's classification system of the living cycads in 1992. But in practical application, infrafamilial taxa, i.g. subfamily, tribe, subtribe should be used sparingly.