<p>Oil and gas pipeline accidents not only caused casualties, economic losses and environmental pollution, but also brought great panic to the public. In order to prevent and reduce oil and gas pipeline accidents, it is necessary to study the main causes of oil and gas pipeline accidents. Its purpose is provide targeted safety measures for accident prevention and control. In this article, the main causes of oil and gas pipeline accidents based on improved TOPSIS method are studied. Firstly, a causal network of oil and gas pipeline accidents based on complex network theory is constructed. Secondly, by analyzing network importance evaluation indicators of the nodes, the determination of the main causes of oil and gas pipeline accidents are transformed into the multi-attribute decision-making evaluation of the importance of accident causal network nodes. Thirdly, a main causes determination method for oil and gas pipeline accidents based on improved TOPISIS method is proposed. The proposed method combines complex network theory, multi-attribute decision theory and improved TOPSISI method, and can address the issue of the significant impact of the correlation between node importance evaluation indicators in the causal network of oil and gas pipeline accidents on decision-making results. Subsequently, the method is applied to the study of main causes and preventive measures of an oil and gas pipelines in central China. Based on the mentioned analysis, targeted safety measures are put forward to prevent oil and gas pipeline accidents. Therefore, this study can provide decision-making basis for oil and gas pipeline accidents safety management.</p>