By analyzing the daily precipitation data from 20:000 BST to next 20:00 BST in Henan, Shandong, Anhui and Jiangsu provinces, the persistent and strong precipitation process(PSPP) over the Huaihe River valley from 1961 and 2006 is defined. Based on the NCEP data, the synthesis method is used to analyse the variation characteristics of atmospheric circulation during and before the PSPP. Results show that,before and during the PSPP,1)The blocking high near the Ural Mountains becomes weaker,while the blocking high to the north of the Lake Baikal and near the Sea of Okhotsk becomes stronger; 2)The western Pacific subtropical high extends to the north and to the west at 500 hPa,whereas it shows obvious extension to the west and almost no extension to the north at 850 hPa;3)The scope of the South Asia high extends obviously. Especially, the height at 200 hPa over the north the Huaihe River valley increases dramatically, and the 200 hPa high level jet center over the East China-Japan changes remarkably as well.The low level jet at 850 hPa is related to the westward extension of the western Pacific subtropical high.And the weakening of the high pressure near the Ural Mountains, the southward-moving of the cold air, and the increase of east-west atmospheric pressure gradient are all beneficial to the formation of the low level jet.