[en] Traditional airplane magnetic field models simplify geomagnetic field values as constants, overlooking changes to the model coefficient brought by gradually variational magnetic field which reduces the model accuracy. This paper puts forward an aircraft magnetic field model under geomagnetic gradient change. The geomagnetic gradient change is adopted the truncated singular value decomposition (TSVD) to solve multicollinearity in the model solving. It is proposed to use the coefficient obtained from the truncated singular value as initial conditions and utilize recursive damped least square (RDLS) to conduct adaptive adjustment to model coefficients aiming at the coefficient variation of induction field and Eddy Current Field caused by the geomagnetic field. The simulation outcome indicates that the method boasts a high magnetic compensation effect. (paper)