Abstract: According to the characteristics of overseas hydrocarbon exploration,starting from the principles of'two steps,five conditions and two levels',the geologic risk assessment methods of overseas hydrocarbon exploration have been discussed.By taking five necessary conditions for hydrocarbon accumulation as analytic objects,at the initial assessment stage,the geological elements existence probability of play were analyzed on the basis of'data quantity,data quality and level of geological understanding';at the detailed assessment stage,the geologic sub-factors which affected the hydrocarbon accumulation process were fully taken into consideration to carry out a comprehensive geologic risk probability analysis.