I have spent the last three weeks between China and Taiwan and I've now learned enough about both sides of the story to know better than take sides. However, I keep wondering why nobody intervene during the Chinese civil war in a similar way the USA did in Korea to fight communism?
By Taiwan I take it you mean the Kuomintang and Chiang Kai-shek?
If so, then the US was hugely involved. The Truman administration sent tens of millions of dollars to the Nationalist government, stationed American troops in China to protect strategic Nationalist areas, and equipped and trained Nationalist troops.
Eventually, however, the weakness of the Kuomintang, both through internal corruption and external defeats, caused the US to withdraw support from the regime in 1948.
It is important to remember the differences between intervention in Korea vs. China. In many ways, the Communist takeover of China informed much of American Cold War policy in Asia. After China, American officials reacted more seriously to threats of Communism in Asia, following the doctrine of containment, which meant stopping new Communist takeovers.
Do you mean militarily? Or just with economic and materiel support?
"during the Chinese civil war"
Meaning before or after the Nationalist government's evacuation to Taiwan ?