Abstract: The earth's lithosphere tectonic characteristics will cause magnetic anomaly,This paper uses MF6 model,get the magnetic anomaly in the Western Yunnan.Through the description and analysis of magnetic anomaly,in contrast to the geological tectonic division,we found good corresponding relationship between them.And further research proved the geomagnetic anomaly caused mainly by residual magnetization in Western Yunnan.The result has important significance for the history of tectonic movement and reduction palaeogeographic distribution in Western Yunnan.