Abstract: Coordinate transformation is a problem which can be frequently encountered during cooperatively completing certain surveying and mapping work. However, as related to their own security and interests, the partners do not want to disclose their input The paper first proposed privacy preserving coordinate transformation and designed corresponding transformation protocol. Based on the above protocol, a protocol for Distance Measure of Different Coordinates was developed and the two's correctness, security and efficiency were analyzed further. In preserved privacy，the problem of privately determining polygonal similarity was successfully solved in the paper,which was also applied to the judgment of target positioning accuracy.

Key words: Secure multi party computation, Coordinate transformation, Distance measure