This paper researches Dagang Oilfield's new energy sustainable system against denial of service (DoS) attacks. Firstly, the current development status of new energy in Dagang Oilfield is illustrated. Then, the common types and principles of DoS attacks are presented, and the weak links of Dagang Oilfield's new energy system and the possible harms are investigated. The system dynamics theory is applied to modeling of the new energy system of Dagang Oilfield, and finally, strategies to resist DoS attacks at both the technical and management levels are developed, which adopt intrusion detection system (IDS) and intrusion prevention system (IPS) on the technical level, and establish a perfected security management system on the management level. The presented multi-dimensional and multi-level strategies improve the system security and anti-attack ability, guarantee the stable operation of new energy system, and provides security for the sustainable development of the oilfield.