Abstract: Since Hobbes, Thucydides’ real attitude towards the Athenian political system has aroused controversy among scholars. Among them, the prevailing view is that Thucydides was a critic of Athenian democracy, and the overall performance of Athens in the Peloponnesian War was disappointing. By examining the performance of Athens during the plague, the Sicilian expedition, and after its defeat, the paper tries to prove that in Thucydides’ works, the Athenian political system and people showed great resilience when the city-state was in serious crisis, and the character of the Athenian political system was mainly shaped by three elements: the political judgement of the people in the Athenian democratic system, the tradition of freedom of the city-state developed in Athens since the expulsion of the tyrant families, and the practice of gradually building a maritime empire since the Persian War. These three elements together shaped the character of the Athenian political system, enabling Athens to maintain its liberal tradition when the city-state was in peril, and the people to make decisions in the public interest of the city-state in most cases.