Abstract: An adaptively robust filter based on Bancroft algorithm and GPS two-stage filter in GPS navigation is developed,in order to control the influences of the dynamic model disturbances,nonlinear problems and outlier existing in measurements.A numerical example is given to demonstrate the ideas involved.It is shown that the new algorithm not only resists the influences of omitted high-order items on the estimated states of navigation,but also controls the outlying kinematic model errors and measurement outliers.