华北地区是我国重要的粮食生产基地，而干旱灾害是影响该地区可持续农业的最突出因 素之一。以华北地区冬小麦关键生育期为切入点，基于SPEI-3 和大尺度环流等数据，借助游程理 论和聚类分析等手段，解析冬小麦生育期干旱事件空间分异规律，探讨干湿时空变化特征及驱动 因素。结果表明：1961—2021 年华北地区冬小麦生育期呈湿润化态势，尤其是孕穗期—成熟期；冬 小麦生育期干湿变化空间差异较大，河北省、河南省及山东省等地湿润化趋势明显，而山西省干化 现象突出；河南省及周边冬小麦全生育期干旱发生频率高、持续时间短，而河北省和山东省北部等 地干旱持续时间长、发生频率低、严重程度高，不同生育期干旱事件空间结构聚类模式不同；冬小 麦全生育期、出苗期—分蘖期、越冬期—拔节期和孕穗期—成熟期SPEI-3 与环流因子存在很强的 关系，主要影响因子依次为热带北大西洋指数、太平洋北美型指数、北极涛动指数和厄尔尼诺3.4 区海温距平指数，研究结果可为华北地区农业抗旱减灾决策提供支撑。

Abstract：The North China region is one of the important grain production bases in China, while climatic drought is the main natural disaster affecting agricultural production, always resulting in immense lose for the agriculture. Hence, exploring the spatiotemporal evolution and formation mechanism of drought in North China is an important basis for a quantitative understanding of drought mechanisms as well as the scientific prevention and control of drought disaster risk, insuring regional and even national food security. based on SPEI-3 and largescale circulation data, this study investigated systematically the spatial variation pattern of drought events during the growth period of winter wheat and its potential influencing factors from the perspective of key growth stages, by combining run length theory, cluster analysis and wavelet transform coherence methods. The results showed that the climate during the growth period of winter wheat in North China from 1961 to 2021 has been becoming moist, especially from the booting stage to the maturity stage, with humidification in Hebei, Henan, and Shandong provinces, and drying tendency in Shanxi province. Henan Province and its surrounding areas were characterized by larger frequency and shorter duration of drought were in during the growth period of winter wheat, while droughts in Hebei Province and northern Shandong Province were characterized by long duration, low frequency and high severity. The spatial clustering patterns of drought event appeared different during individual growth period. SPEI-3 was strongly related to circulation factors during the entire growth period, emergence-tillering period, overwintering-jointing period, and booting-maturity period of winter wheat, with critical influencing factor of TNA, PNA, AO, and NINO34, respectively. The results of this study could provide regional specific valuable insights for agricultural drought resistance and disaster reduction decision-making in North China.