Abstract: In the present paper，both cladistic analysis and phenetic analysis were conducted to evaluate the phylogenetic relationships of the Taxodiaceae based on an extensive literature review and study of herbarium． In the cladistic analysis，the Sciadopityaceae was chosen as outgroup．The polarity of characters was determined mainly according to outgroup comparison，fossil evidence and generally accepted viewpoints of morphological evolution．By the result of compatibility analysis，character 2(leaf type)，which possessed a much higher coefficient than others whether or not its polarity was altered，was deleted． Finally，a data matrix consisting of all the extant nine genera and 24 characters was analyzed using Maximal Same Step Method，Synthetic Method，Evolutionary Extremal Aggregation Method and Minimal Parallel Evolutionary Method，and four cladograms were generated，of which only the most parsimonious one (Fig．1)was presented for discussion. The cladogram shows that the Taxodiaceae are assorted along five lines of evolution： 1)Metasequoia；2)Sequoiadendron，Sequoia；3)Cryptomeria；4)Glyptostrobus and Taxodium；5)Cunninghamia，Athrotaxis and Taiwania． Ten genera(including Sciadopitys)and 59 characters were used in the phenetic analysis．The phenogram(Fig．2)indicates that Sciadopitys is a very distinct group with remote affinity to the other genera，and the Taxodiaceae are divided into four groups：1)Sequoia，Sequoiadendron；2)Athrotaxis，Cunninghamia and Taiwania；3)Cryptomeria，Glyptostrobus and Taxodium；4)Metasequoia． Based primarily on the result of cladistics，with reference to that of phenetics，the main conclusions were drawn as follows：(1)Generic relationships：Cryptomeria should be considered the most primitive genus in the extant groups of the Taxodiaceae. Glyptostrobus and Taxodium, close to Cryptomeria, are sister taxa and relatively primitive groups. Sequoiadendron and Sequoia are closely related and intermediate advanced. Metasequoia is a more or less isolated taxon, relatively close to Sequoiadendron and Sequoia. Cunninghamia. Athrotaxis and Taiwania might represent a single lineage and form a very advanced group, of which Taiwania may be the most specialized. (2) Systematic treatments: The authors support the viewpoint that Sciadopitys should be treated as an independent family, and suggest that the Taxodiaeae should be divided into five tribes. Systematic arrangements are as follows: Taxodiaceae Warming Trib. 1. Cryptomerieae Vierhapper Gen. 5. Sequoia Endl. Gen. 1. Cryptomeria D. Don Trib. 4. Metasequoieae Pilger et Melchior Trib. 2. Taxodieae Benth. et Hook. Gen. 6. Metasequoia Miki ex Hu et Cheng Gen. 2. Glyptostrobus Endl. Trib. 5. Cunninghamieae Zucc. Gen. 3. Taxodium Rich. Gen. 7. Cunninghamia R. Br. Trib. 3. Sequoieae Wettstein Gen. 8. Athrotaxis D. Don Gen. 4. Sequoiadendron Buchholz Gen. 9. Taiwania Hayata

Key words: Taxodiaceae, Phylogeny, Cladistic analysis, Phenetic analysis