After Japan surrendered, the Chinese civil war broke out. At the time, Tan took sides with the Communists. He even sent telegrams to then American President Truman and the US Senate and House of Representatives, expressing his opposition to the American support of the Nationalist government engaged in the civil war.
日本投降後，國共內戰接著展開，陳嘉庚此時已一面倒向共黨政權，甚至致電美國總統杜魯門及參眾兩院，反對美國援助國民政府進行內戰。