Abstract: Petroleum resource assessment is the basis of exploration decision, and the results from assessment have a great effect on exploration investment and process of exploration. This paper divides the evaluation methods into three main types, i.e. material balance method, reservoir volume method and discovery process method. The superiority and disappearance of each type of method are also presented in the paper. The methods exist at present can not provide the information of quantitative spatial distribution. In order to decrease the exploration risks and increase the exploration benefits, quantitative prediction of petroleum spatial distribution will be the main development trend of resource appraisal.