Abstract: Based on the operational meteorological data,it is found that as usual MCC appeared in July and August,this MαCS was formed in a macro-scale warm ridge with southwester low level jet (LLJ) transporting warm moist air to the area.The emerging of the conditions was because the western Pacific subtropical high had exceptional northward in that spring.Although in the sense of climate the Yellow River Reaches was in a typical spring,still the synoptic scale condition at that time was quite similar with that in midsummer when MCS (and MCC) emerged,somewhere even stronger (the intensity of LLJ e.g.),so it was very favourable for MαCS.At the profile of the radar echoes,the convections at the first stage were several regularly arranged cells,then they turned into a narrow arc echo band.At last they became a width extended but intensity weaken echo region behind the strong echo band.The second precipitation event lasted from evening to nighttime on 17,April,2003 with greater intensity.The difference in the infraredimages from geostationary meteorological observation satellite was that its major axis was towards northeast-southwest,especially after combining with several convective cells in the southwest at about midnight and became an area cloud band extending from northeast to southwest,the whole cloud system seemed to be a short cold front cloud band.The radar echo presented to be fluctuation.Compared with the first MαCSs heavy precipitation,the divergence of vapor flux and vapor flux vector in the second MαCSs heavy precipitation was even more favourable for MαCS.