Abstract: Referring to the baseline assessment methods commonly used in other ecosystems, this paper studied and discussed the baseline assessment methods of the reference points for environmental damage caused by marine oil spill, and analyzed and put forward the indicators system of screening the reference site for environmental damage caused by marine oil spill. The "11•22" Sinopec Donghuang oil pipeline leakage and explosion accident in Qingdao city, Shandong province were taken as an example for application. Through comparison and verification, the environmental damage baseline obtained from the selected reference sites is close to the actual historical monitoring data of the case. The selected reference sites can represent the environmental state before the occurrence of oil spill in the assessment area, indicating that the reference sites screened by the established indicator system can be applied to the determination of damage baseline. The established screening indicator system of environmental damage by oil spill is relatively scientific and effective, the indicators used in the screening system are common and easy to obtain, and the indicator system has strong operability in practice.