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The atmospheric circulation around the Tibetan Plateau (TP) exhibits a substantial 10–20‐day quasi–biweekly oscillation (QBWO), profoundly impacting weather and climate locally and remotely. Understanding the factors influencing the generation of QBWO over the TP (QBWOTP) and its physical mechanism is crucial. This study has investigated the influence of multi–timescale and land–atmosphere interactions on the generation of the QBWOTP in surface potential vorticity (SPV), a valuable tool for characterizing the mechanical and thermal variabilities in mountain forcing, based on a 2014 case study. Results indicate that in the free atmosphere, the summer monsoon onset over the Bay of Bengal induces a northward shift in the westerly jet toward the TP, manifested as an increase in low‐frequency zonal winds. This shift facilitates the propagation of wave trains, leading to atmospheric quasi–biweekly potential temperature anomalies (θa) over the TP through a multi‐timescale interaction. Additionally, the TP's surface thermal forcing and arrival of wave trains trigger anomalous upward motion and increase cloud cover. The resultant decrease in net short‐wave radiations and increase in net long‐wave radiations contribute to variations in surface potential temperature (θs) over the TP. As θa and θs evolve, the difference between them enlarges, resulting in the generation of the SPV QBWOTP. Given the relationship between the QBWOTP and downstream rainfall, this study could provide novel insights into understanding and predicting downstream rainfall QBWO. Plain Language Summary: The atmosphere around the Tibetan Plateau (TP) exhibits a substantial 10–20‐day oscillation known as the quasi–biweekly oscillation (QBWO). The QBWO over the TP (QBWOTP) significantly impacts weather and climate both locally and in distant regions, making it crucial to understand its generation. We conducted a case study to understand the QBWOTP and its generation mechanism in surface potential vorticity (SPV), a useful tool for examining the dynamic and thermodynamic variations of the TP. Our results indicate that the summer monsoon over the Bay of Bengal affects the TP by causing a northward shift in the westerly jet, leading to wave train propagation and atmospheric potential temperature variability. The surface thermal forcing of the TP and wave trains influence clouds and surface radiation, causing changes in the surface potential temperature. These combined effect of these processes results in the SPV QBWOTP generation, which has important implications for understanding and forecasting downstream rainfall QBWO. Key Points: SPV QBWOTP is dependent mostly on the vertical difference in the potential temperature (θs–θa)Onset of BOBSM influences the zonal wind, wave trains propagation, thereby θa during SPV QBWOTP generation via multi‐timescale interactionWave trains and TP land–air interaction regulate the surface energy balance, leading to the variation in θs during SPV QBWOTP generation [ABSTRACT FROM AUTHOR]