In this paper, errors of demagnetization correction of rock and ore samples are analyzed and discussed. It is clear that when the NK＇ of rock and ore samples around 1, demagnetization correction coefficient is very high and unsteady, after demagnetization correction, error of the apparent magnetic susceptibility （K＇） and the demagnetizing factor（N） will cause higher errors of magnetic susceptibility （K） and remanent magnetization （Jr）, and might even induce a wrong result with negative magnetic susceptibility （K） and remanent magnetization （Jr）. The magnetic parameters are difficult to interpret magnetic survey data. Standardized rock and ore samples should be used for improving precision of the magnetic parameters measurement, reducing the errors of apparent magnetic susceptibility and demagnetizing factor, and interpreting magnetic survey data.
