A pot experiment was conducted to study the effects of decomposing leaf litter of blue gum (Eucalyptus globulus) on the growth and photosynthetic characteristics of spinach (Spinacia oleracea). Four levels of leaf litter addition were set as follows: CK (the control, 0 g/pot), L30 (30 g/pot), L60 (60 g/pot), L90 (90 g/pot) and L120 (120 g/pot), and each pot contained 10 kg of soil for mixing with the leaf litter. The results showed that: (1) A low dose of leaf litter (L30) did not affect the biomass accumulation of spinach on the 30^th day of decomposition, while a medium and high dose of leaf litter (L60-L120) suppressed it visually (P < 0.05); When the duration of decomposition reached 50 d, both L30 and L60 stimulated the accumulation of the biomass of spinach, and no significant difference existed between L90 and CK, while the effect of L120 was still suppressive, indicating a languishment of the inhibition of leaf litter decomposition. (2) The effects of leaf litter decomposition on the photosynthetic pigments of spinach also varied with increasing time and leaf litter amount. Positive effect was observed at L30 and L60 in the chlorophyll content, while L120 converted this effect. However, the effects of these leaf litter treatments were not apparent until the 40^th d. (3) The intercellular CO₂ concentration (Ci), stomatal conductance (Gs) and transpiration rate (Tr) were all significantly higher than those of the control (P < 0.05), while the peak value of the net photosynthetic rate (Pn) appeared at L30, which were statistically the same with that under the CK at L60 and L90, moreover, significant decrease was only observed at L120 (P < 0.05); (4) As for the parameters of light response curve and CO₂ response curve, the apparent quantum yield (AQY), maximum net photosynthetic rate (P_max), near light saturation point (Lsp), light compensation point (Lcp), dark respiration rate (Rd), RuBP apparent carboxylation efficiency (CE) and photorespiration rate (Rp) all showed a trend of increasing at L30 and decreasing gradually with increasing leaf litter, while CO₂ saturation point (Csp) and CO₂ compensation point (Ccp) increased with the increase of leaf litter. In sum, a small amount of blue gum leaf litter (treatment L30 in present study) could promote the chlorophyll content and the light / CO₂ use efficiency of spinach, and thus stimulated its growth, but a high level of leaf litter (treatment L90 and L120) reversed this effect.