Abstract: In recent years,EROI is a new evaluation method for energy producing from the view of energy flow.This paper compares the thermal and quality factors method of EROI,introduces two-level analysis table,and shows its applicability by using oil field data.Furthermore,it focuses on the analysis of two important elements,namely energy quality factors and energy conversion coefficient by using the Divisia index.Finally,taking Daqing Oilfield for an example,its EROI from 2001 to 2012is calculated,and the impact factors and optimization method for EROI increasing are also offered.