Autocorrelation coefficients of data of geomagnetic total intensity of neighboring periods from six stations in Henan province are calculated respectively. The relationship between the coefficients and earthquakes is analysed. The results show there is a good correlation between them.The original time is usually within 1~8 months after the lowest value of the coefficients.Empirical formulas between magnitude,anomalous area of the autocorrelation coefficients and epicentral distance for every station are statistically obtained. By using the empirical formulas of three or more stations and intersection method, the magnitude and epicenter of coming earthquake can be forecasted. The test results show the method is basically feasible.