Monsoon precipitation is the major driver of agricultural productivity in the Myanmar Coast, it is crucial to quantify and understand recent changes in precipitation during the monsoon season over this region. By using multiple precipitation datasets, we demonstrate that total precipitation during monsoon season over the Myanmar Coast has increased slightly but not significantly, but precipitation during the onset and withdrawal phases of monsoon season exhibit a significant increasing trend during 1979–2015, and the contribution of precipitation during the two phases to total monsoon precipitation has increased significantly. The increased precipitation during the onset phase over the Myanmar Coast directly results from the earlier onset of the South Asian Summer Monsoon in recent decades, which is associated with the phase transition of the Inter-decadal Pacific Oscillation in the late 1990s. And the precipitation increase during the withdrawal phase is directly due to the enhances of the ascending motion and convection around this region, which is dynamically correlated to the anomalous cyclone-like circulation around the Bay of Bengal as well as the strengthening of the cross-equatorial flow around the equatorial Indian Ocean.