Abstract: Effects of age, type of auxin and treatment concentration on rooting ability of Japanese larch (Larix leptokpis) were systematically studied under mist irrigation on the open field. And general rooting effect for different treatments was e-valualed and the best combinations of auxin type × concentration were selected for different ages of Japanese larch ortet. Based on subordinate function values, the results was evaluated. Once the bests combinations selected are used to treat cuttings taken from test progeny of 12. 5 and 8. 5 years old Japanese larch, 78. 8% and 92. 5% rooting percentage can be obtained , which meant that rooting ability for vegetative propagation of older Japanese larch tree was dramatically improved. Variance analysis of three factors showed rooting ability of Japanese larch was extremely or obviously influenced by age (A) of donor tree, type of auxin (B) and treatment concentration (C). Extremely difference could be found in rooting percentage, root number per cutting, root length and rate of one-side rooting among ages or auxin treatment. There were obvious on extreme difference sparely in rooting percentage, root number per cutting and one-side rooting rate, and the in- teraction effect of three factors (A×B×C) or interaction effects between factors (A×B, A×C and B×C ) also gave extreme influence to most of rooting characters. From results of comparing the treatment of type of auxin and concentration, and interaction effect between them for different age of the donor trees, regular changing in rooting character cannot be fund obviously in this experiment.