Based on 1995~1998 datasets at 4 AWS over the Tibetan plateau during the experiment of Sino-Japan cooperation on Asian Monsoon and 1995~1996 daily NCEP/NCAR reanalysis data,study is performed of the features of LFO phase structure with its relation to summer regional rainfall.Results show that the 30~50 d LFO of sensible/latent heat flux has the same phase,with the exhanced phase corresponding to less plateau rainfall and v.v..The propagation of 200 hPa LFO zonal wind reveals that the Plateau is a sink region for LFO in winter of 1995~1996.Further evidences show that 200 hPa LFO zonal wind,which is regatively correlated with LFO station pressure and lags about one week to LFO surface sensible heat flux with a phase difference of 3π/8,is positively (negatively)correlated to summer rainfall in Lhasa (north China).