1989年的「天安門事件」是中共建政以來遭遇的一次重大政治危機，學生、民眾群集表達對其統治的不滿，中共最後決定動用武力壓制。彭真是中共元老級的政治人物，他在此一事件中的角色問題，中共出版的官方傳記對於敏感環節多予迴避，西方學界和相關著作則無甚了解。彭真在事發之時雖然已無任何黨政要職，但並沒有缺席，而是努力協助中央處理相關事態，也發揮重要影響。彭真在此事發展過程中的態度，其實存在微妙的變化。他一度支持中央總書記趙紫陽主張的溫和與對話方針，但在鄧小平決定戒嚴後改變立場，並且認為繼續堅持己見的趙紫陽失職犯錯。其後，彭真憑藉其多年累積的黨內聲望和資歷，以及先前擔任全國人民代表大會常務委員會委員長的影響力，完成中央使命：勸退全國人大常委會領導成員，使之放棄提前召開全國人大常委會議討論當前政治焦點問題的計畫。彭真成功的政治遊說，讓中共中央得以排除可能來自全國人大常委會的政治干擾，更加緊握處理學潮示威的主導權和機動性。彭真的相關作為雖有助中共維繫政權，但也扼殺了全國人大常委會難得嘗試展現自主性的機會。

For the Chinese Communist Party (CCP), the Tiananmen Square protests of 1989 were a great political crisis to its rule. During this event, many students and masses gathered in the heart of the nation's capital to express their dissatisfactions and grievances towards the CCP, to which the Party Center led by the paramount leader Deng Xiaoping finally decided to brutally crackdown on the protests by the force. Peng Zhen had already retired from the important post of senior CCP's Politburo member and the Chairman of the Standing Committee of the National People's Congress (NPC) before the eruption of the Tiananmen Square protests. However, as an influential old revolutionary, he was still deeply involved in the political process, wielding enormous influence and assisting the Party Center led by Deng in coping with the severe political incident. It is noteworthy that Peng initially supported Party General Secretary Zhao Ziyang's moderate approach in dealing with the student protests. However, after knowing Deng's decision to impose the martial law in the nation's capital, he quickly changed his attitude to firmly stand with Deng, and began to criticize Zhao. Moreover, Peng made good use of his high revolutionary status and prestige, successfully dissuading the leading members of the NPC's Standing Committee from convening the emergency meeting before the scheduled time to independently handle the student protests. Peng's efforts assisted the Party Center led by Deng in putting the NPC's Standing Committee under its tight controls; therefore, Deng and his loyal followers could adopt their wishes of using a heavy-handed-approach to put an abrupt end to the protests. Peng helped the Party Center pass through the political crisis in 1989 to maintain it rule. However, Peng's actions also seriously damaged the increasing autonomy and authority of the NPC, which he devoted himself to building when he was the head of this political organ.