Abstract: Studying the secular variation characteristics of the main magnetic field in the Pacific region is significance to reveal the time evolution and secular variation of the dipole window in the region. This paper uses the latest international geomagnetic reference field IGRF13 model data to analyze the secular variation characteristics of the main magnetic field in the Pacific region from 1900 to 2020. The results show that the spatial distribution of the main magnetic field in the Pacific region from 1900 to 2020 conforms to the distribution characteristics of the ‘Pacific dipole window’. The secular variation of the main magnetic field in the region is slow, north of the equator, and rapid, south of it. Dipole field components change slowly, while non-dipole field components change faster. The secular variation of non-dipole field is dominated by westward drift, but the westward drift rates of each component are significantly different. The westward drift rates of vertical component (Z) and north component (X) are 0.23°/a and 0.21°/a, respectively, which are close to the global non-dipole westward drift rate of 0.2°/a; the westward drift rate of the eastward component (Y) is 0.17°/a, which is lower than the global non-dipole westward drift rate. The secular variation of Y component is distorted near 34°N and shows a slow eastward drift in the North Pacific, which may be related to the subduction of the paleoplate at the core-mantle boundary between 30°N and 45°N in the northern Pacific.