Aims Compound-leaved plants commonly grow better than simple-leaved plants, but it is unknown about how leaflet growing position influences leaflet trait variations and its correlations in compound leaves. Our aim was to address this question with a model tree species Fraxinus mandshurica. Methods Fraxinus mandshurica, a typical compound-leaved tree in northeastern China, was selected as a focal plant species. We measured leaflet thickness (LT), leaflet area (LA), leaflet dry matter content (LDMC), specific leaflet area (SLA), leaflet nitrogen content (LNC), and leaflet phosphorus content (LPC) across leaflet growing position in the compound leaves of F. mandshurica. We analyzed its leaflet trait variations with leaflet growing position and examined if leaflet growing position significantly affected leaflet traits using the least significant difference (LSD) method. Similarly, we analyzed the relationships among leaflet traits and examined if leaflet growing position significantly affected these relationships using the standardized major axis (SMA) method. Important findings (1) LT, LA, LDMC and LNC decreased with leaflet growing position (from the tip to the base of a compound leaf), but SLA and LPC increased with leaflet growing position. LT and LA were significantly variable with leaflet growing position. (2) Within a compound leaf, there was an isometric