In the twenty-fourth year of Yuan Zhizheng (1364), Zhu Yuanzhang became the throne of Wu and promoted Chang Yuchun to Pingzhang political affairs. After the Wu army occupied Wuchang, Chang Yuchun immediately occupied all parts of Jing and Hu. He followed Zuo Xiangguo Xu Da to conquer Luzhou, and also conquered the sand pits, Maling, Niupi and other places in Linjiang, and captured Chen Youliang's Zhizhou Deng Keming. Then he moved to Ji'an (now Ji'an, Jiangxi), and Chang Yuchun took advantage of the void to capture Ji'an. Soon, he went to besiege Ganzhou.
Xiong Tianrui, the defender of Ganzhou, insisted on resisting and often encountered Chunjiu and could not attack. Zhu Yuanzhang sent an envoy to Chang Yuchun and said: "You can't kill more people when attacking the city, if you get the land and don't have the people, then what's the point of us occupying the land?" So he often dug trenches and tree fences in the spring to besiege Ganzhou City. After six months of garrisoning outside, Xiong Tianrui's manpower and financial resources were exhausted, so he had to surrender, and Chang Yuchun really didn't kill innocents. Then, Chang Yuchun took advantage of the majesty of the army to persuade the enemies of Nanxiong and Shaozhou to surrender, and then returned to pacify Anlu and Xiangyang.
In August of the twenty-sixth year of Yuan Zhizheng (1366), after Chang Yuchun and Xu Da led an army to conquer Huzhou, Chang Yuchun was awarded the title of deputy general and led the army to attack Pingjiang occupied by Zhang Shicheng. Often meet the spring garrison Tiger Hill. Zhang Shicheng secretly sent troops to approach Chang Yuchun, and Chang Yuchun defeated the other party and almost captured Zhang Shicheng alive. At this time, outside the city of Suzhou, Xu Da ordered the army to erect a wooden tower, the famous Japanese enemy building, a total of three floors, each floor can be used to cast crossbow arrows and muskets to the city, and there is Xiangyang to bombard the city, the city is very panicked. After holding each other for a while, other generals broke through the Fengmen, Chang Yuchun also broke through the Changmen and entered the city of Suzhou, Zhang Tucheng and other captured guards were sent to Jiankang together, Zhang Shicheng did not surrender, hanged himself. Chang Yuchun was promoted to the important military affairs of Zhongshu Pingzhang this time and was named the Duke of Hubei.