Abstract: From March to May, 2010, a pot experiment was conducted to investigate the effects of Eucalyptus grandis leaf litter at its early stage of decomposition on the growth and photosynthetic characteristics of Cichorium intybus. Four treatments with different application rate of the leaf litter, i.e., 0 g·pot^-1 (CK), 30 g·pot^-1 (A₁), 60 g·pot^-1 (A₂), and 90 g·pot^-1(A₃), were installed. Each pot contained 12 kg soil mixed with the leaf litter, and then, C. intybus was sown. The growth indicators of the C. intybus were measured at the 30, 45, 60, and 75 d after sowing, and the photosynthetic characteristics of the C. intybus in treatment A₃ were studied after the seedlings third leaf fully expanded. At each measured time, the biomass accumulation and leaf area growth of C. intybus in treatments A₁, A₂, and A₃ were inhibited significantly. At the early stage of the leaf litter decomposition, the synthesis of  photosynthetic pigments of the C. intybus seedlings was inhibited significantly, and the inhibition effect was getting stronger with the increasing amount of the leaf litter addition. The diurnal change of the seedlings photosynthetic rate in all treatments showed a bimodal curve with midday depression, the stomatal conductance and water use efficiency had the same variation trend with the net photosynthetic rate, and the total diurnal photosynthesis decreased in the order of CK > A₁> A₂> A₃. The GCMS analysis showed there were 33 kinds of small molecule compounds released gradually with the decomposition of the leaf litter, among which, allelopathic substance terpenoid dominated.