Abstract: Pinaceae is the largest family in gymnosperms，containing about 230 species in 10 genera．Based mainly on morphological characters of leaves，long and short branches，it is generally classified into three subfamilies，i．e．Abietoideae (Keteleeria，Abies，Pseudotsuga， Tsuga，Cathaya，Picea)，Laricoideae (Larix，Pseudolarix，Cedrus) and Pinoideae (Pinus)．Five types of karyotypes was defined in this family．(1) Pines Type [24(22)m+O(2)sm，Pinus]；(2)Silver-Fir Type [(22～14)m+(2～10)sm(st)，Cathaya，Picea， Tsuga，Cedrus，Keteleeria，Abies];(3)Larches Type[12m十12sm(st),Pseudotsuga， Larix];(4)Oregon-Douglas-Fir Type(10m+12sm+4t，Pseudotsuga menziesii)；(5) Golden-Larch Type[4sm+40t(4SC)，Pseudolarix)．In the light of comparative analysis of the karyotypic data，the evolutionary sequence of the genera may be as follows：Pinus (Pines Type)→Cathaya，Picea，Tsuga，Cedrus，Keteleeria，Abies (Silver-Fir Type)→ Pseudotsuga，Larix (Larches Type，Oregon-Douglas-Fir Type)→Pseudolarix (Golden-Larch Type)．This sequence and the relationships among the genera (excl．Pseudolarix) are clearly shown in Figure 1．The monotypic genus Pseudolarix with the karyotype K(2n)＝44=4sm+40t(4SC) is rather different from all the other genera (2n＝24) of the family not only in chromosome number and karyotype，but also in its peculiar habit，and a number of morphological and anatomical characters．Therefore，it seems reasonable to raise Pseudolarix to subfamily level，Pseudolaricoideae L．C．Li，and to reduce the three previously recognized subfamilies to three corresponding tribes (Abieteae，Lariceae and Pineae)，which belong to another subfamily Pinoideae. Pseudotsuga and Larix, having the karyotype K(2n)= 24=12m+ 12sm(st), should constitute the Tribe Lariceae, and Cedrus [K(2n)= 24=(20,18)m+(4,6)sm] be placed in Abieteae as its karyotype is similar to that of the tribe.Based on the karyotypic data, a new system of Pinaceae is proposed which is supported by data from morphology, anatomy, phytochemistry, immunology, biochemistry, embryology and paleobotany, etc. Meanwhile, the comments on the previous systems of the Pinaceae are made in this paper. Subfam. I Pinoideae Pilger 1926 Keteleeria Carr. 1866 2n=24 Tribe 1 Pineae Parl. 1868 Abies Mill. 1754 2n=24 Pinus Linn. 1753 2n=24 Tribe 3 Lariceae Takhtajan 1956 Tribe 2 Abieteae Spach 1842 Pseudotsuga Carr. 1867 2n=24(26) Cathaya Chen et Kuang 1958 2n=24 Larix Mill. 1754 2n 24 Picea Dietr. 1824 2n=24 Subfam. II Pseudolaricoideae L. C. Li Tsuga Carr. 1855 2n=24 Tribe 4 Pseudolariceae L. C. LiCedrus Trew 1757 2n=24 Pseudolarix Gord. 1858 2n=44

Key words: Pinaceae, Karyotype, Evolution, Phylogeny