The hydrocarbon vertical microseepage theory is the basic theory for oil and gas exploration. Nevertheless, the study of this theory has been very insufficient, which affects the deepgoing study and extensive application of oil and gas geochemical exploration. Therefore, the strengthening of the study in this aspect is quite necessary. Starting with the concept of the oil and gas microseepage action, this paper deals with the complexity of the hydrocarbon vertical microseepage process, sums up the present research situation and major development in the study of this theory, and forecasts its development trend.