Basic methods to study the Earth's magnetic field are direct observations, of the spatial distribution of the magnetic field as well as its variations over of land, sea and in the surrounding space. Therefore, the scientists in geomagnetic field over the world have established the equation to compute the geomagnetic field based on the expansion of the Gauss Equation. In this work the authors have used the calculating formula of IGRF 11, these calculations are available for mapping the major components of geomagnetic field on the territory of Vietnam, East Sea, and adjacent areas. Calculations were derived from the Website www.noaa.gov/geomag-web/#grfwmm, and calculated data were used to construct geomagnetic map for the researched area. The obtained results are orientation data for the maritime research as well as for computing magnetic anomalies and the circular variation study.