Abstract: In order to study the method and effect of Cotoneaster hjelmqvistii micro-shoots rooting in vitro, the stem sections of Cotoneaster hjelmqvistii plantlet in vitro were inoculated in the sterilized medium supported by soil and the cultural bottles were located in green-house, then the rooting culture was completed under different shading conditions or during different culture periods respectively. The opening and closing of stoma was observed and the transplanting experiment was done for the Cotoneaster hjelmqvistii plantlet rooted in vitro in green-house. The results show that shaded by two-story shade net, 87.5% of the stem sections rooted when cultured from April 12 to May 22,and 98.1% of the stem sections rooted when cultured from September 2 to October 12. Under dark conditions, the stoma closing rate of the Cotoneaster hjelmqvistii plantlet cultured in green-house was 32.5%, which was obviously higher than that of the plantlet cultured in the constant temperature room（5.0%）, and this indicated that the plantlet cultured in green-house had been acclimated during the stage of rooting. Without acclimation in opened bottles, the Cotoneaster hjelmqvistii plantlet cultured in green-house were transplanted with lump into the soil, under the conditions without plastic film covering and spraying, and when the relative air humidity was about 50% after noon, the survival rate of the plantlet was 90.0%, obviously higher than that of the plantlet cultured in the constant temperature room （30.3%）. These results can obviously reduce the culture cost of the Cotoneaster hjelmqvistii plantlet in vitro and promote the micro-propagation technology application of Cotoneaster hjelmqvistii to the production.

Key words: Cotoneaster hjelmqvistii, micro-shoot, green-house, in vitro rooting, survival rate