Abstract: Selection principles for materials,geometry and dimension of the magnetic marker in the magnetic navigation system of outdoor mobile robot are introduced in detail.Based on analyzing the features of various magnetic sensors,the HMC1002 magnetoresistive sensor is chosen as the sensing elements to detect magnetic signals.A magnetic ruler including 13 magnetoresistive sensors is made to measure magnetic field of the magnetic marker.The magnetic ruler is installed on the front bumper of the vehicle at a relatively high position,and the low installation location problem in the magnetic navigation system with Hall-effect sensor is solved with magnetoresistive sensors.An improved sequential algorithm is brought forward,and by subdividing the offset range with the given threshold value,more precise magnetic localization results can be obtained according to the ratio of the neighboring sensors.The experimental results show the precise measurement with the improved sequential algorithm.