The invention discloses a geomagnetic measurement method based on a split type suspended spherical coil. The method comprises the steps that a measurement system is installed; under the situation thatpower is not supplied to a compensating spherical coil, a tester host measures a geomagnetic total field through the compensating spherical coil; under the situation that power is supplied to the compensating spherical coil, a measured value is recorded as the geomagnetic horizontal component when reaching the minimum; the tester host supplies power to a bias spherical coil, the bias spherical coil applies a bias magnetic field in the east-west direction, and a resultant magnetic field of the bias magnetic field and geomagnetic total field is calculated to obtain a relative magnetic declination; other geomagnetic parameters are calculated by using the geomagnetic total field, the geomagnetic horizontal component and the relative magnetic declination. The structure of the split type suspended spherical coil adopted by the geomagnetic measurement method is very simple, a magnetic field generated inside the coil is more uniform, a magnetic field outside the coil attenuates more quickly,the external radiation is small, and the sampling frequency can be effectively improved.