Abstract：Because the similarity transformation method applied in practice for coordinate transformation is not so accurate in general to unify different coordinate systems, the collocation method is applied for coordinate transformation from the 1980 Xi’an coordinate system to 2000 Chinese geodetic coordinate system and the local error accumulation and distortion are considered in the collocation method. The computed result of an actual sample shows that the accuracy of transformed coordinates is evidently improved with the collocation method than with the similarity transformation method.
