Abstract: According to the characteristics of the reference points in mining areas which were laid at early time and are easy to shift ，the theory of high breakdown contamination rate for the coordinate transformation with the reference points' displacements is proposed to ensure the quality of coordinate system transformation for the high precision GPS control network and eliminate the impact of the displacements existed in the transformation reference points on the transformed results.Then the estimation model for the coordinate transformation parameters and the quality evaluation system for transformed GPS network are established.Taking a Yanzhou mining area for example，the results show that the model can choose a reasonable and stable reference points and remain the high precision characteristics of GPS technology，also provide a high precision coordinate datum for the mining area.

Key words: Reference point, Displacement, High breakdown contamination rate, Quality evaluation, Coordinate transformation