Using the objective analysis and intensive observation period data,the large-scale features of Meiyu front associated with intense rainfall in low-and middle-reaches of the ChangJiang River in June 1999 are studied.The results are as follows:(1)The total precipitation has a west-east distribution and is concentrated within a narrow rainband,the southern and northern boundary of rainband is clear during Meiyu period of 1999.(2)The maintaining of westerly flow which come form the Bay of Bengal and southwest flow which around along the northwestern periphery of the western Pacific subtropical high provide favorable large-scale condition for the Meiyu front rainstorm.The presence and maintaining of upper-and lower jet provide favorable lifting mechanism,at the same time the character of neutral convective instability stratification provide favorable instability mechanism in the low and middle levels.(3)The convergence of moisture is obvious in the low level of troposphere over the area of Meiyu front.The transportation of moisture mainly come from the Bay of Bengal and the western Pacific ocean,and then monsoon trough in South China Sea is a moisture transport channel from tropic sea to China mainland and has important effect in moisture transportation to Meiyu front zone.(4)Two cores appeared in high levels of troposphere which corresponding to the upper westerly-and easterly-jet in the cross-section of spatial averaged zonal wind u;the cross-section of spatial averaged meridional wind v dominates the southerly under 400 hPa and the northerly above 400 hPa;the potential instability stratification locates on northern and southern sides of Meiyu front zone,which are restricted by the downdraft and the instability energy could not be released,and then in these areas have not intense rainfall.