Abstract: 【Objective】Identify the optimum multi-factor combination for propagation and the mechanism of rooting of shoot cutting propagation of Monarda didyma, with the goal of providing the theoretical basis and technical support for shoot cutting propagation of ground cover plants as applied in urban forests of cold and arid regions.【Method】Based on the orthogonal test of shoot cutting propagation, the optimized multi-factor combination for propagation was determined. Anatomical and physiological studies, as well as a morphological study of M. didyma were conducted to reveal the histologic origin of adventitious roots, rooting type, the basic law of nutrient metabolism, and the response of protective enzymes against the dynamic fluctuation of harmful substances.【Result】The optimal combination for shoot cutting propagation of M. didyma was A₂B₁C₂D₃(the substrate with the ratio of the vermiculite and peat soil is 7:3 and the cutting taken from the top with length 10 cm, ABT concentration to 1 000 mg/kg)with 100% root balls forming within 23 d. Different positions of cuttings on the branch substantially affected root ball forming rate. The root primordia originated by the induced pattern, and the mixed rooting mode produced the roots. The callus formations on the cutting base were independent from adventitious root production. There were significant and highly significant correlations between the dynamic variation contents of soluble protein, POD, SOD and MDA.【Conclusion】Shoot cuttings is suitable for the propagation of M. didyma. Crucial factors of shoot rooting were not totally dependent upon the existence of root primordium in the cutting slips, which should be a plant hereditary character and dependent upon use of key techniques. The response mechanism of soluble proteins and the plant enzyme protection system to the dynamic changes in harmful substances under stress played an important role in the formation of root primordium and the callus.