Abstract: When developing a GPS monitoring system based on Google Maps，a problem is found out that there is an offset between the Google Maps’ latitude and longitude position and its real position.The study show that the offset can be corrected using correction database.But it is very inefficient that correcting so much position data.Therefore，four improved algorithms for correcting a fixed precision offset are brought out.The experiments data indicate that these algorithms are valid and they can be used in different situation.

Key words: Google Maps, map offset, correction algorithm

摘要： 基于Google Maps开发GPS监控系统时，存在Google Maps的地图经纬度坐标与实际的经纬度坐标有较大的偏移的现象。研究发现，通过修正数据库可以进行不同精度的偏移修正。针对修正大量的位置数据时的低效率问题，提出了固定精度下不断改进的四种修正算法，并通过实验得出了不同算法适用于不同情形的结论。

关键词: Google Maps, 地图偏移, 修正算法