Abstract: With more energy imported by China, the business on construction and operation of multinational oil and gas pipelines is increasing rapidly. The unique political attributes of multinational oil and gas pipelines are likely to bring about complicated and prominent political risks to the pipelines, which may not only trigger hazardous risks, but also induce risk effects. According to the system characteristics of multinational oil and gas pipelines, the influence factors, formation process and occurrence conditions of the catastrophe effect of political risk diffusion on the multinational oil and gas pipelines were analyzed based on the swallowtail catastrophe model by introducing the risk entropy theory. Based on the essence of catastrophe effect of political risk diffusion on multinational oil and gas pipelines, the suggestions were put forward to cope with the catastrophe effect by prohibiting the formation of dissipative structure and risk decoupling in the pipeline system, providing reference to the political risk management of multinational oil and gas pipelines to some extent.