When only the distance difference between the predicted value and the observed value of a single landmark exceeds the threshold, the landmark is determined to have changed its position due to external interference.Assuming that the JTH landmark is subject to external interference, the covariance matrix Pm, J is expanded to increase the uncertainty of the landmark prediction, make the system state more inclined to the AGV pose and other landmark observation results, and thus make the update of the system state closer to the true value.