The low Reynolds numbers of small UAV will result in unfavorable aerodynamic conditions to support controlled flight.
And as operated near ground, the small UAV will be affected seriously by low-frequency interference caused by
atmospheric disturbance. Therefore, the GNC system needs high frequency of attitude estimation and control to realize
the steady of the UAV. In company with the dimensional of small UAV dwindling away, its GNC system is more and
more taken embedded designing technology to reach the purpose of compactness, light weight and low power
consumption. At the same time, the operational capability of GNC system also gets limit in a certain extent. Therefore, a
kind of high speed navigation algorithm design becomes the imminence demand of GNC system. Aiming at such
requirement, a kind of non-linearity matrix reduction approach is adopted in this paper to create a new high speed
navigation algorithm which holds the radius of meridian circle and prime vertical circle as constant and linearizes the
position matrix calculation formulae of navigation equation. Compared with normal navigation algorithm, this high
speed navigation algorithm decreases 17.3% operand. Within small UAV"s mission radius (20km), the accuracy of
position error is less than 0.13m. The results of semi-physical experiments and small UAV's auto pilot testing proved
that this algorithm can realize high frequency attitude estimation and control. It will avoid low-frequency interference
caused by atmospheric disturbance properly.