A single-chip three-axis magnetic field sensing device is provided. This single-chip three-axis magnetic field sensing device comprises a substrate, a first sensing module, a second sensing module, a third sensing module and at least one coil. The substrate includes a surface. The first sensing module comprises at least one first magnetoresistive element and is configured to sense a first magnetic field component substantially parallel to the surface. The second sensing module comprises at least one second magnetoresistive element and is configured to sense a second magnetic field component substantially parallel to the surface. The third sensing module comprises at least one third magnetoresistive element and is configured to sense a third magnetic field component substantially perpendicular to the surface. Wherein one of the first magnetoresistive element and the second magnetoresistive element and the third magnetoresistive element is disposed right above or right below the at least one coil.