The mechanism of hydrocarbon vertical micropercolation in oil and gas accumulation has been a point at issue in the basic theoretical study of oil and gas geochemical exploration. There exists much controversy concerning the genetic mechanism of the nearsurface oil and gas geochemical anomalies. Based on the measurement of waterpercolating artificial core rate by the selfdesigned modeling experiment device under the condition of normal temperature and high pressure together with digital simulation results available as well as case studies of hydrochemical exploration, the authors hold that it is impossible to form oil and gas micropercolating anomalies via vertical migrating through deep compaction water of the basin and meteoric water and penetrating oil and gas accumulation unless there exist ideal channels such as large fissures and faults at the depth. This is to say that the mechanism of migration with water is not the major genetic mechanism of the oil and gas anomalies. The results obtained by the authors provide experimental evidence for the study of the genetic mechanism of oil and gas anomalies.