Abstract: Hybrid ovules from crosses between Populus simonii×P.pyramidalis,P.simonii×P.euphratica,P.simonii×P.lasiocarpa,P.simonii×P.wilsonii and P.×741 reciprocal combination containing immature hybrid embryos at various developmental stages are excised for culture.Plantlets are obtained successfully. The basal medium is 1/2MS.1.Effects of different concentrations of IAA and BA on adventitious shoot buds and leafy shoots formationare tested.The optimum differentiating medium is 1/2MS+IAA 0.01mg/1+BA 0.1mg/1.In the absence of IAA,1/2MS+BA0.1mg/1 is also efficient.2.Effects of different concentrations of NAA and IBA on roots formation are tested.The optimum rooting medium is 1/2MS+NAA 0.01—0.02mg/1 or 1/2MS+IBA0.1—0.5mg/1.The leafy shoots may also root on 1/2MS without supplemented with NAA or IBA. The developmental stages of contained embryos at the time of inoculation is influence on the percentage of germination and the growth of the cultured ovules.The percentage is rather low,33%,for the early heart-shaped embryos and the seedlings are very weak and difficult for further growth.The percentages are rather high,50—100%,for the heart-shaped,torpedo-shaped and the cotyledonary elongation embryos and the seedlings are healthy and may lead to shoot buds initiation and leafy shoots formation.Rooting plantlets are transferred to soil and grow normally. Histological sections show that the adventitious shoot buds dediffe-rentitiate from the epidermal,cortex,endodermis and even pericycle cells of the radicle and the hypocotyle.