Real-time calculating method for roll angle and rotation speed of rotating body based on uniaxial geomagnetic sensors is deeply analyzed. An improved mean filtering method is adopted

which can effectively reduce the interference error of geomagnetic signals. According to the characteristics of low-cost geo-magnetic device

by using the periodic sampling points number T of geomagnetic signal and zero point C

a method for realtime prediction of roll angle and rotation speed of a spinning object is proposed

and formulas for calculating of the number T of periodic sampling points under variable cycles are derived. The experimental results show that the new method can realize real time calculation of the roll angle and rotate speed of rotating body under the condition of using uniaxial low cost magnetoresistive device

and it has practical significance to reduce detecting cost.