To understand how Cunninghamia lanceolata seedlings respond and adapt to extant and future climate conditions, a factorial air (ambient, open-top chamber (OTC)) and soil (ambient, +4 ℃) warming experiment was conducted at Chenda observing point of the Fujian Normal University's Forest Ecosystem and Global Change Research Station in Sanming, Fujian Province. We assessed the effects of warming on leaf functional traits of C. lanceolata seedlings. Air warming was implemented by OTC passive warming and soil warming by soil cable heating. The responses of leaf functional traits, including leaf photosynthetic characteristics, morphological traits, and stoichiometry of C. lanceolata seedlings, were examined during the one-year study. The results showed that there was no significant effect of both air warming and soil warming on leaf photosynthetic rates (Pn) and water use efficiency (WUE) in April and July, but Pn was increased significantly by soil warming in November. Both air warming and soil warming increased WUE in November. Air warming significantly increased specific leaf area and leaf water content, and decreased leaf thickness; however, there was no significant effect of soil warming on these traits. Both air and soil warming significantly increased leaf nitrogen (N) concentration, but only simultaneous air and soil warming treatments significantly increased leaf phosphorus (P) concentration. Thus, simultaneous air and soil warming treatments are more beneficial to the growth of C. lanceolata seedlings in terms of leaf functional traits.