This present study suggests a method to calculate the SO2 flow rate from a source area to receptor areas on a regional scale using Ozone Monitoring Instrument (OMI) SO2 products, surface in situ SO2 data, and the hybrid single particle Lagrangian integrated trajectory (HYSPLIT) model. The method was implemented to calculate the SO2 flow rate from continental Asia to northeast Asia and the Northwest Pacific Ocean. For the high SO2 events when SO2 was transported from continental Asia to Japan via the Korean Peninsula on 22–24 December 2006, the long-range transported SO2 flow rates were 14.0 (21.0) Mg·h−1 OMI·gird−1 at Gangneung (Seoul) in Korea and 4.2 (5.3) Mg·h−1 OMI·gird−1 at Hiroshima (Kumamoto) in Japan. For the long-range transport of SO2 from continental Asia to the Northwest Pacific Ocean on 6–7 October 2008 (9–11 October 2006), the flow rates were 16.1 (16.2) Mg·h−1 OMI·gird−1 at Hokkaido, Japan (Vladivostok, Russia) and 5.6 (16.7) Mg·h−1 OMI·gird−1 at the Aleutian Islands, Northwest Pacific Ocean (Bering Sea). The mean rates of decrease in the SO2 flow rate per 1000 km were also calculated between continental Asia and the receptor areas. Uncertainties in the flow rate estimates were also assessed and discussed.