In 1937, the Second Sino-Japanese War broke out. Because of his outstanding performance in the Battle of Xinkou, Hou Jingru was promoted to Chief of Staff of the 91st Army . At the beginning of 1938, he was transferred to command the 21st Division and fought in the battles of Taierzhuang , Wuhan and Zaoyi. In 1943, he was promoted to commander of the 92nd Army, and awarded the rank of lieutenant general, leading his troops to participate in the Battle of West Hunan.