Based on the daily precipitation data at 77 stations in Jiangnan area of China and the NCEP/NCAR reanalysis data,the different time scale low frequency precipitation in Jiangnan area and the principal component of 850 hPa low frequency meridional wind in East Asia are employed to construct a multivariable lagged regression(MLR) model,which is applied to complete the daily extended range forecast test for the low frequency precipitation in Jiangnan area during May-July of 2011.Results show that the average prediction skill of the 50-70 d low frequency precipitation in Jiangnan area is up to 0.76,which is able to predict accurately the period of persistent heavy rainfall and the conversion of positive and negative phase of low frequency precipitation.The hindcast experiments from 2001 to 2012 show that the MLR model can predict well the low frequency precipitation in Jiangnan area ahead 30 days in the years of stronger or normal 50-70 d oscillation.The model results also show that the development and evolution of 850 hPa low frequency meridional wind are the outstanding signals for the change of low frequency precipitation in the next 30 days and can be considered a key factor of extended range heavy precipitation prediction in Jiangnan area in early summer.