Abstract: To explore the effect of tree age of ancient Platycladus orientalis on rooting of cuttings propagated from them and the physiological mechanism during the cutting process, the cuttings of 5, 100, 300 and 700years P. orientalis female trees were used as scions respectively, and the phloem at the base of the cutting at rooting stages0 d（S1, stage of before cutting）, 35 d（S2, stage of callus formation）, 65 d（S3, stage of adventitious root formation）, 95 d（S4, stage of adventitious root elongation） were harvested as the materials and the dynamic changes in the physiological indicators were measured, and the rooting rates and the numbers of rooted cuttings were counted respectively. The results showed that both of the rooting rates and the numbers of rooted cuttings propagated from ancient P. orientalis were significantly less than those of five years ones（P＜0.05）. The nutrients（total sugar and total protein）, activities of antioxidative enzymes（polyphenol oxidase（PPO）,peroxidase（POD）, superoxide dismutase（SOD）） and hormones（Indole-3-acetic acid（IAA）, zeatin riboside（ZR）） contents of the cuttings of five years donors were significantly more than those of ancient P. orientalis donors at all rooting stages, indicating that the high levels of these substances facilitated the rooting of the cuttings（P＜0.05）. The contents of malondialdehyde（MDA）, abscisic acid（ABA）, and gibberellin（GA） showed a significant increase with increasing tree ages, indicating that the cuttings of ancient P. orientalis contained more harmful substances and hormones that inhibited rooting（P＜0.05）. The nutrients（total sugar and total protein） and hormone（IAA and GA） contents showed a trend increased first and then decreased throughout the four stages, and it was worth noting that the contents reached maximum value at S3. On the contrary, ABA contents at S3 were significantly lower than that of another three stages（P＜0.05）. The results indicated that the stage of adventitious root formation（S3） was a critical stage during the cutting process（P＜0.05）. The larger the ratio of ω（IAA）/ω（ABA） and ω（ZR）/ω（ABA） were, the better for adventitious root formation. Tree ages significantly affected the rooting rate of P. orientalis cuttings, but there was no significant difference in the rooting rate of cuttings of ancient P. orientalis of different ages. Therefore, the reasons for difficulties in rooting of cuttings from ancient P. orientalis were mainly attributable to the lack of nutrients（total sugar and total protein）, activities of antioxidative enzymes（PPO, POD, and SOD） and endogenous hormones（IAA and ZR） beneficial to rooting.