Together with Chen Cheng and Tang Enbo, Hu, a native of Zhenhai, Ningbo, formed the triumvirate of Chiang Kai-shek's most trusted generals during the Second Sino-Japanese War.

One of Chiang Kai-shek's favourite students, he took part in the Northern Expedition as commander of the 2nd Regiment, 1st Division, First Army.

During Hu Zongnan's initial success, he was able to overrun the communists' base in Shaanxi and forced the communists to evacuate most of their governmental bodies to the east of the Yellow River, the nationalist troops were dangerously overstretched in guarding the newly conquered regions and spread thin.

[2] The American Time magazine claimed Hu beat his chest like Tarzan when he was frustrated or angry.

In March, 1948, at Ichuan Peng Dehuai led Communist forces to launch a surprise attack against Hu Zongnan's forces, inflicting 20,000 casualties upon them, and drove all the way with 60,000 soldiers into southern Shaanxi province to reach Sichuan, General Hu requested immediate help from Muslim Governor Ma Hongkui, who sent two Muslim cavalry divisions.