Abstract: Practice of the field mobile geomagnetic survey and many studying results show that geomagnetic survey may be become one of the improtant approaches in earthquake prediction.However,the continuity,integrity,accuracy and reliability of geomagnetic survey data are still facing some problems.In order to solve these problems,we gave the current status of the location sign in mobile geomagnetic survey a thorough analysis.The results show:if there is no strict location sign in mobile geomagnetic survey,it will cause serious problem.So it is essential improving the current location signs to keep the accuracy of field survey.The specific implement scheme is given here,including:setting up location sign by ourselves;building stone mark;adding secondary mark;choosing good secondary location signs.