In complex road conditions such as urban tunnels and remote mountainous areas, where satellite navigation system signals arepartially or totally occluded, the accuracy of a vehicle's GNSS/INS integrated navigation system was degraded.Thus, an odometer-assisted high-precision integrated navigation method was proposed in this paper. The combined filtering mode in the method could realize adaptive switching between the GNSS/INS and DR/INS combined modes according to the changes in the vehicle's environment.Additionally, in the combined navigation method, the three-dimensional reckoning position error was extended to the conventional combined navigation filter state. Further, the scale factor error and installation angle error of the odometer could be accurately obtained offline using the odometer error calibration method. However, it is necessary to bind the odometer error parameter to the integrated navigation system in a subsequent use. The vehicle tests reveal that the maximum position error of the integrated navigation system in a single direction of a 7-km signal occlusion scene is 8 m, and the position error is less than 3 m throughout the test.Therefore,the vehicle GNSS/INS integrated navigation system can provide high-precision positioningin complex road conditions.