Map matching is a type of popular localization approaches for mobile robot autonomous navigation in indoor environment. Global localization is to fmd the best correspondence between current local map and the global map. Local map and global map are represented with comer points that are sorted counterclockwise. Relative position relation of comer points is computed in local and global map and used to search matched pairs. Map matching based on ordinal map improves the searchmg efficiency. Map matching based on relative position relation avoids frequent coordinates transformation. All these techniques have been implemented on our mobile robot ATRVII equipped with 2D laser range scanner SICK.