Using the original data of 3 m eddy correlation system and 10 Hz turbulence data at Shiquanhe station and Linzhi station, which are respectively located at the southwestern and southeastern Tibetan Plateau, obtained during "the 3rd Tibetan Plateau atmospheric scientific experiment", station observation data provided by China Meteorological Administration, JRA-55, and GPCP (Global Precipitation Climatology Project) daily reanalysis data in July and August of 2014, the diurnal variations of surface layer meteorological elements and turbulent changes under the background of 10-20-day low frequency oscillation in two stations are studies respectively. The results are as follows. The 10-20-day low frequency component of circulation fields in the upper and lower troposphere and water vapor fields and heat sources at the two stations are opposite during their dry and wet phases. The variations of low frequency surface sensible and latent heat fluxes have influences on precipitation, and these influences are different in the western and eastern Plateau. The low frequency oscillation at Shiqianhe station propagates from west to east, whereas the oscillation at Linzhi station propagates from east to west. Thus, there are two types of low frequency oscillations from different origins. Surface layer meteorological elements and turbulent flux have obvious diurnal variations in the dry and wet phases. The highest temperature usually appears at 1400 BJT (Beijing time) but at 2000 BJT in the dry and wet phases at Shiquanhe station. Based on Bowen ratio, it can be found that the latent heat is dominant throughout the day at Shiquanhe station in the wet phase, while latent heat is dominant before 0600 BJT and sensible heat is dominant after 0600 BJT during the dry phase. At Linzhi station in both wet and dry phases, sensible heat is always dominant before 0800 BJT and latent heat is dominant after 0800 BJT. The average kinetic energy of turbulence and average wind speed are positively correlated at the two stations, and the vertical momentum is transported downward while heat and moisture are transported upward.