關於彭真對中共早期對外關係與工作的參與程度和活動情況，現有的中、西文獻皆對之注意不夠、甚至是低估忽視。彭真在「文革」前經常出席毛澤東主持的中央高層會議（尤其是政治局常委會），直接與聞重大對外決策的形成過程；他以中央書記處第二號人物的身分，也時常過問黨和政府對外部門和事務的領導工作。彭真的對外活動主要表現在四個方面：一、協助中央處理對蘇聯的關係，多次參與中蘇高層會談，身處與蘇鬥爭和辯論的最前線，每以強硬的反「修正主義」者面貌示人。二、頻繁接見外賓，一方面介紹和辯護中共的治國政策和結果；另一方面宣傳和推銷中共反「蘇修」主張和對外政策。三、以政黨外交或議會外交為名出國訪問，力在增進邦誼和拉攏友黨，在國際上為中共爭取「反帝」、「反修」和「反殖民主義」的戰略夥伴。四、主持首都外交，既向其他共黨國家首都兜售執政經驗，也藉由與非邦交國城市的往來，拓展雙邊實質關係；同時著力發揮北京市作為中共對外窗口和講台的角色。彭真在對外關係的忠於職守和恪遵使命，可謂是毛澤東激進對外政策的一名主要幫手和得力推手。如此讓彭真聞名國際和享譽國內，中共中央在對外事務上也有對之進一步委以重任的趨勢；惟因彭真在「文革」初倒台而中斷告止。彭真在「改革開放」時期因其職權分工和年邁高齡，他在對外工作上的重要性和活躍度，已不能與「文革」以前的盛況相比。

Peng Zhen’s role in the external relations of the People’s Republic of China has received little research attention, and has been underestimated. Before eruption of the Cultural Revolution, Peng often attended central meetings, especially the Politburo Standing Committee meetings, presided by Mao Zedong, and participated in decision-making of major foreign policies. Besides, as the second-ranking leader of the Central Secretariat under Deng Xiaoping, Peng had the power and authority to lead and direct works of the International Liaison Department of the Chinese Communist Party and the Ministry of Foreign Affairs. Peng’s main roles and activities in this policy field include the following: first, Peng devotedly assisted the Mao-led Party center to deal with Sino-Soviet relations, always being the vanguard for criticizing and opposing so-called revisionists; second, Peng often received foreign guests on behalf of the central authority, zealously propagandizing the nation’s domestic and foreign policies; third, Peng visited many countries in order to strengthen relationships with other socialist states or to find strategic partners in anti-imperialism, anti-revisionism and anti-colonialism; fourth, as the Party Secretary and mayor of the PRC’s capital, Beijing Municipality, Peng enthusiastically pushed the capital towards capital diplomacy to support and supplement official governmental diplomacy.Consequently, Peng was one of the most fervent activists in promoting and carrying out Mao’s radical foreign policies. In contrast with his active and important role in foreign relations during the pre-Cultural Revolution period, in the Reform and Opening-up period, Peng no longer played prominent roles in foreign affairs, mainly due to his advanced age and relatively limited political power and status.