Using conventional meteorological observation data, observations from mesoscale automatic weather stations over Henan, Doppler weather radar data, FY-C/D satellite cloud images and NCEP/NCAR reanalysis data with 1°×1° resolution, we have conducted a compara-tive analysis of the structures and the causes of β-mesoscale convective systems (MβCS) during "7.14" extreme precipitation event and "8.02"thunderstorm gale event in Henan. The results show that the MβCSs with similar morphological features as detected by satellite in the two events show different severe convective weather characters due to the differences in dynamic, water vapor and thermodynamic instability. MβCS characterized by extreme precipitation is shown a north-south belt convection system formed in the mixed precipitation region, while MβCS by thunderstorm gale is shown a west-east bow echo developed in cloud-free region in the radar chart. The former results in heavy rainfall due to the merging of convective clouds, but the latter results in thunderstorm gale due to theγ-mesoscale wind disturbance. Both MβCSs form in the low-level high energy areas and the mid-and low-level convergence areas (about 100 km wide) where vertical relative vorticity (divergence) presents a"positive-negative (negative-positive)"alternate distribution from bottom to top, and, where secondary circu-lation develops when the descending motions are on both sides of narrow vertical ascending motion area."7.14"extreme precipitation event is characterized by a deeper convergence zone, quasi-saturated wet area and vertical ascending motion in the mid-and low-level, and larger precipitable water vapor, stronger warm advection in low-level during the initial convection period and weak cold inflow in boundary layer triggering convection, while"8.02"thunderstorm gale event has stronger condition instability, greater vertical wind shear of 0-2 km height and convergence line in boundary layer which plays an important role of triggering convection.%利用常规观测资料以及河南省中尺度自动站资料、多普勒雷达产品、FY系列卫星云图和NECP 1°×1°再分析资料，对比研究河南“7.14”极端强降水和“8.02”雷暴大风过程中β中尺度对流系统(MβCS)的结构和成因。结果表明：“7.14”和“8.02”过程中卫星监测的MβCS具有相似形态，但因其动力、水汽和热力不稳定条件差异造成二者具有不同强天气特征，极端降水型MβCS在雷达图上表现为混合性降水区内形成的南北向带状对流系统，对流云合并导致强降水，而雷暴大风型MβCS在雷达图上表现为晴空少云区内发展的东西向弓形回波，γ中尺度大风速扰动导致雷暴大风。两个MβCS均形成于低空高能量区内，垂直相对涡度(散度)自下向上呈现“正负(负正)”交替特征，中低层辐合区宽约100 km左右，狭窄的垂直上升运动区两侧为下沉运动，形成次级环流。“7.14”过程中，中低空辐合层、准饱和湿区及垂直上升运动区相对深厚，整层可降水量较大，对流初期低层暖平流较强，边界层弱冷入流起对流触发作用；“8.02”过程中，条件不稳定明显偏强，0—2 km垂直风切变偏大，边界层辐合线起重要的对流触发作用。
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