The data distortion of geochemical exploration(espeCially，distortion at high-value point)di—rectly affects determination of geochemical anomalies．According to the distributional characteris—tics of oil／gas surface geochemical exploration data and the principle of probability statistics，thispaper proposes a probability discrimination method by which the distorted data of geochemical ex—ploration can be processed at the earlier stage of work．This method has yielded good results inthe application of data．