Abstract: Corylus trees are monoecious and unisexual plants. The male inflorescences and female buds begin to differentiate in June of the current year and blossom in March next year. The infructescence begin to develop in May and the nut mature in early August in Beijing region. The higher the latitude is, the later the phenophase comes. The light saturation point of photosynthesis of hazel plants is relatively low, and the bimodal peaks are also far away from noon light time, indicating that hazel plant adapts to the shade and weak light conditions. The saline-alkali, low temperature, drought and other stresses conditions may have adverse effect on hazel growth, lead to abnormal physiological indicators, and decrease the photosynthetic capacity. Hazel trees have dichogamous characteristics, different organs have different maturity stage. The required cooling capacity of male inflorescences, female flower buds and leaf buds are 336-1 176 h, 504-1 344 h, 672-1 512 h, the required calories are 687.0-998.5 GDH℃, 998.5-3 496.1 GDH℃, and 2 546.5-4 180.3 GDH℃. Water loss in late winter and early spring is the direct cause of shoot shriveling. The shriveling resistance varieties have high value of the vessel density, total vessel area, vessel/xylem ratio, number of xylem rays and their cross-sectional area, average length of vessel cells and average diameter, and low value of the pore width. The regulatory genes which involve traits such as cold resistance, shoot shriveling resistance, saline-alkali tolerance, inflorescences differentiation and self incompatibility are cloned. The expression and the functions of regulatory genes are analyzed in order to lay a foundation for molecular-assisted selection breeding. The pollen characteristics, stigma receptivity, pollination and fertilization process and the abortion of ovary and ovule were systematically studied in order to provide guidance for improving the pollination effect and preventing blank shell problems.