Abstract: The trial plantations with 15 Alnus cremastogyne provenances were planted in 6 sites along the middle and lower reaches of Yangtze River according to a split plot design.Four hundred and sixty two wood cores were sampled from 3 sites of 6 year old plantations for measuring and analyzing the wood density and fiber length of 15 A. cremastogyne provenances.The results showed that provenance means for wood density was 0.382 3 g·cm-3 and fiber length was 1 247 9 mm.It also proved that there existed significant differences among provenances in wood quality and fiber length.The interaction between provenance and site in wood density was not significant,however,that between provenance and site in fiber length was significant.Meanwhile,in Jiangxi Province,there also existed significant difference among provenances and families in fiber length,however,significant difference in wood density was only existed among provenances.Wood density and fiber length were not significantly correlated.The relationship between wood quality and growth characters was also weak,hence the selection of wood property or growth character can be conducted independently.Genetic parameter analysis showed that the provenance heritability and family heritability of wood density were 0.564 8～0.661 8 and 0.285 7～0.653 5,while that of fiber length were 0.255 3～0.789 5 and 0.290 5～0.452 8.The models of the changes of wood density and fiber length with the age and the correlation of early stage and late stage were set up.It is proved that the feasible age for genetic selection is 6 years old.From the viewpoint of wood density,the feasible age for culturing pulp wood is 10～11 years old.