Horses, for example, are a recurring and popular subject in Xu's oeuvre in which he imbued the animal with meanings of strength and spirit. His horse paintings sold so well that it is said he painted hundreds of them while in Singapore. "Tens of thousands of horses galloped at the Jiangxia Hall," was a saying from back then.

Xu also depicted eagles and lions－the other common subjects of his work, which symbolized an unremitting spirit in the face of difficulty－in his paintings to motivate Chinese people to stand against Japanese invasion and do whatever they could to support Chinese soldiers and victims of the war.