To explore the interaction of iron (Fe) with phosphorus (P) deficiency and aluminum (Al) toxicity coupling stress in acidic soil and its effects on Al tolerance of Cunninghamia lanceolata, we conducted sand culture method with four treatments: Control (CK), Al stress (Al), P deficiency and Al toxicity coupling stress (-P+Al) and P deficiency and Al toxicity coupling stress without Fe (-P+Al-Fe) under controlled conditions in this study to investigate the effects of exogenous application of Fe on the growth, photosynthetic physiology, Al and Fe contents and resistance physiology in leaves of C. lanceolata seedlings under P deficiency and Al toxicity coupling stress by using superior genotype seedlings of C. lanceolata YX11. The results showed that: (1) Al stress could significantly inhibit the growth of Chinese fir seedlings, and the growth inhibition induced by Al was further aggravated by normal iron supply under the coupling stress of phosphorus deficiency and aluminum toxicity (-P+Al), -P+Al-Fe significantly alleviated the growth inhibition induced by -P+Al treatment. (2) Compared with CK, the photosynthetic pigment content, chlorophyll fluorescence parameters including maximal fluorescence (F_m), variable fluorescence (F_vm), PSⅡ potential photochemical activity (F_vm/F_o), PSⅡ maximal photochemical efficiency (F_vm/F_m), photochemical quenching coefficient (qP), actual maximum quantum yield (QY) and net photosynthetic rate of Chinese fir leaves all decreased in different degrees under various stress treatments. However, a more significantly decreasing amplitude of above indexes was observed in -P+Al treatment as compared with -P+Al-Fe treatment. (3) The activities of SOD, POD, CAT and APX in leaves of C. lanceolata were significantly increased under different stress condition when compared with CK, and the increasing amplitude of these enzyme activities in -P+Al treatment was significantly lower than that in -P+Al-Fe treatment, which in turn leads to higher accumulation of malondialdehyde in -P+Al treatment as resulted by the formation of hydrogen peroxide. (4) Different stress treatments all resulted in a significantly higher accumulation of Al content in both roots and leaves of C. lanceolata seedlings as compared with CK, while no significant difference of Al content was noted between -P+Al-Fe and -P+Al treatments. Moreover, a significantly higher of Fe content in both roots and leaves of C. lanceolata seedlings was found in -P+Al treatment as compared with -P+Al-Fe treatment. The above results demonstrated that under phosphorus deficiency and aluminum toxicity coupling stress, compared with Fe deficiency, normal Fe supply could significantly promote the accumulation of Fe in plants, thus the increase of antioxidant enzyme activity was inhibited, and increased the accumulation of hydrogen peroxide, which in turn caused degradation of photosynthetic pigments and irreversible damage to the plasma membrane and photosynthetic reaction center, resulted in significant decrease of photosynthetic efficiency and ultimately the growth inhibition induced by Al was aggravated.