Abstract: Taking eight-year-old sweet cherry varieties ‘Brooks’ ‘Meizao’‘Zaodaguo’ and ‘Wanhongzhu’ as test materials, the flowering phenology, floral organ characteristics, pollen characteristics, and stigma receptivity were measured to systematically understand the biological characteristics of sweet cherries in the Alar region, in order to provide reference for efficient cultivation of sweet cherries in the Alar region.The results showed that the four sweet cherry varieties had similar flowering periods, with ‘Brooks’ having a faster development rate, and ‘Zaodaguo’ and ‘Wanhongzhu’ having longer flowering periods.The corolla diameter and petal diameter of ‘Meizao’ were both the largest, while ‘Brooks’ and ‘Zaodaguo’ were prone to the phenomenon of multiple pistils.All four sweet cherry varieties were of medium pollen type, with ‘Brooks’ having a maximum polar axis length of 49.07 μm.The maximum length of the equatorial axis ‘Meizao’ was 24.53 μm.The outer wall decoration of pollen grains was striped.The stigma of ‘Wanhongzhu’ had the strongest receptivity, and ‘Zaodaguo’ had the highest single flower pollen quantity.When the sucrose concentration was 10 g·L^-1,the pollen germination rate was the highest, with ‘Zaodaguo’ having the highest pollen vitality.There were differences in the flowering biological characteristics of different varieties of sweet cherries.It was recommended to choose varieties with similar phenological periods and high pollen vitality for planting to improve fruit setting rate and yield.