Abstract: The trends of developing micro-satellites are high reliable,high accuracy,completely autonomous and low cost.GPS has been applied in low earth orbit spacecraft,because it has the advantages of low cost,high accuracy and low power consumption.The GPS pseudo-range was used as measurement values,and the measurement still could be obtained even when the GPS visible stars were few.The orbit accuracy was improved and the cost was reduced.The memory attenuated extended Kalman filter(MAEKF) was presented.Through adjusting covariance matrix,the application of historic data in the new data was reduced,so the influence of orbit perturbation on orbit accuracy was reduced.The simulation reslts show that the MAEKF is better than extended Kalman filter(EKF) in accuracy.When visible GPS stars are few,it still can realize information fusion.