The coordination between plant functional traits reveals the main strategies to adapt to specific habitats. The plant growth rate may be correlated with functional traits during early growth. To explore the variation characteristics of the roots, stems and leaves functional traits and their relationship with the relative growth rate of five introduced evergreen broad-leaved tree species (ie., Ancuba japonica (Thunb). var. Variegata D'ombr.; Adinandra millettii (Hook. et Arn.) Benth. et Hook. f. ex Hance;Distylium racemosum Sieb.et Zucc.; Gardenia jasminoides Ellis in Philos. Trans.; Pittosporum tobira (Thunb.) Ait.) under the Cunninghamia lanceolata (Lamb.) Hook. plantations, the relative growth rate of tree height and basal diameter and 27 morphological and physiological traits of roots, stems and leaves of the five introduced tree species were studied. The results showed that: (1) According to the principal component analysis (PCA), the functional traits of different shade-tolerant trees roots and stems were more closely related than leaves traits. In addition, the coefficients of variation of roots and stems traits in the inter-species were smaller than the leaf area. (2) The trait correlation network between the key traits and relative growth rate in the inter- and intra-species varied greatly. In the inter-specific correlation network, the relative growth rates were significantly positively correlated with most leaves traits, and negatively correlated with most roots and stems traits. The correlations network between key traits and relative growth rates were more complex in the intra-specific relationships. (3) The relative growth rate of tree height was the growth rate indicator with the highest centrality in the relationship network of inter- and intra-species. Leaf area was the highest centrality in the inter-specific correlation network. The Leaf biomass fraction, stem biomass fraction and root dry matter content had the highest centrality in intra-specific correlation network. However, only the leaf area and relative growth rate of tree height showed a significant and positive correlation in inter- and intra-species. Therefore, the leaf area was more suitable variable for predicting the relative growth rate of shade-tolerant tree species under C. lanceolata plantations. Overall, the leaves traits regulate the relative growth rate more than stems and roots traits. The introduction of evergreen broad-leaved tree species with larger leaf areas may be more conducive to reforestation and the construction of efficient multi-layer of C. lanceolata plantations.