In the field prospecting work, the most important thing for geologists is to wait for the data of sample test results. The test period is generally relatively long. In the exploration work of the Dalu manganese deposit, the author's group quickly surveyed the drilling cores of the manganese deposit by X-ray fluorescence instrument. It is found that the measurement data of this method have high accuracy in judging the enriched strata of manganese ore and the interpretation accuracy of orebody. Moreover, the instrument is precise. After calibration, the results of measurement are compared with those of laboratory data. The degree of approximation is very high. Especially for manganese ore (chemical) layer whose grade is more than 5%, the error between the results of measurement and laboratory results is generally less than 7%. It has objective and efficient guiding significance for orebody confirmation, core sampling section and sampling length determination in the field.