Intra-seasonal Oscillation (ISO) with a time scale between 10 and 90 days is one of the most significant climatic phenomena.Abundant observation researches have proved that the ISO of diabatic heating over the Tibetan Plateau (TP) is active,which is not only affected by the low-frequency activity from mid-and high-latitude,but is also affected more significantly by the inter-seasonal thermal forcing of tropics.It is more likely to be an important source of predictability for intra-seasonal prediction.Therefore,it is necessary to understand the ISO of the TP's thermodynamic effect and its propagation.Based on the daily reanalysis data of NCEP/NCAR from 1979 to 2017,the atmospheric heat source is estimated.The characteristics and propagation pathway of Quasi-BiWeekly Oscillation (QBWO) of the atmospheric heat source over the TP in summer are investigated.Results show that the first two leading modes of the quasi-biweekly atmospheric heat source over the TP and its surrounding areas,i.e.the uniform pattern with the load center in the southeast of the TP and the dipole pattern with the southeast-northwest antiphase change in the TP,reflect two different states of QBWO of the atmospheric heat source over the TP during its propagation from east to west in summer.This is mainly because in the middle and upper troposphere of the mid-latitude area,the activities of the quasi-biweekly atmospheric circulation are shown as the propagation of large anomalous cyclones and anticyclones from Northeast China to West Asia from east to west through the TP.When they move near the TP,they increase rapidly,and when they move away from the TP in the west,they decrease obviously.In addition,QBWO of the heat source over the TP modulates the precipitation anomalies in the TP and its surrounding areas,the Bay of Bengal and the Indian Peninsula.However,the further study is needed to explain the physical mechanism of the precipitation anomalies caused by thermodynamic effect from the TP.