Taiwan Strait (TWS) plays an important role in material exchange and nutrient budget between the South China Sea (SCS) and the East China Sea (ECS). This study investigates the variability of the volume transport in the TWS and its response to tropical MJO convection based on the simulated results from a three-dimensional operational numerical model. Validated by the observational data, the model generally reproduced the physical field well. The volume transport in the TWS has strong seasonal cycles as well as higher-frequency variations. The intra-seasonal fluctuations dominate the along-strait currents variability, while the secondary and the last signal are seasonal one and inter-annual variability, respectively. The along-strait wind stress is more important than the pressure gradient induced by north-to-south sea level slope in controlling the variability of the volume transport in the TWS. At intra-seasonal time scales, the volume transport in the TWS varies as the tropical MJO convection moves from Indian Ocean eastward to the western Pacific Ocean. These oceanic anomalies are shown to be related to atmospheric anomalies, with a distinct physical linkage from the tropical atmosphere to the mid-latitude ocean. The tropical MJO deep convection can modify the upper tropospheric heights and a wave train pattern propagating to mid-latitudes is generated. These anomalous upper tropospheric heights modulate the surface pressure and result in a cyclonic anomaly. The upper tropospheric heights anomaly and its corresponding mean sea level pressure anomaly move eastward following the eastward migrating MJO heat source in the tropics from phase 2 to 5. As a consequence, surface winds change as the cyclonic anomaly moves from central China in MJO phase 2 to the east of Japan in MJO phase 5, resulting in a northeast volume transport anomaly during MJO phase 2 and 3, and a southwest volume transport anomaly during MJO phase 4 and 5.