Always thought China was relatively insignificant to the allied victory. Didn’t they just get conquered by Japan then fight a civil war? Why would the allies give them a spot on the security council?
While you wait for fresh answers from qualified experts, you may be interested in some previous threads on the topic.
Why was the UN Security Council given to the PRC? with a detailed response by /u/onetruepapist .
Why was China -- in the midst of a civil war -- added to the UN Security Council? with a detailed response by /u/Drdickles.