During his reign, General Erzhu largely controlled the military and acted in a violent manner, leading Emperor Xiaozhuang to believe that he would usurp the throne.

In 528, Emperor Xiaoming, who was having increasing friction with Empress Dowager Hu, conspired with the general Erzhu Rong to have Erzhu advance on the capital Luoyang to force Empress Dowager Hu to yield power and to kill her lover Zheng Yan (鄭儼) and Zheng's associate Xu Ge (徐紇).

Upon hearing of Emperor Xiaozhuang's ascension, Empress Dowager Hu's generals Zheng Xianhu (鄭先護), a friend of Emperor Xiaozhuang, and Fei Mu (費穆), quickly surrendered, while another general, Li Shengui (李神軌), fled.

Erzhu ordered the imperial officials to welcome Emperor Xiaozhuang into Luoyang while sending cavalry to arrest Empress Dowager Hu and Yuan Zhao.

Fei suggested to Erzhu that since his army was actually small, as soon as the imperial officials realized the situation, they would resist him.

Erzhu ordered the imperial officials to his camp at Heyin (河陰, near Luoyang) under the pretense that Emperor Xiaozhuang was going to offer sacrifices to heaven and earth there, and then surrounded the imperial officials and slaughtered them, killing more than 2,000 of them, including Emperor Xiaozhuang's uncle, the prime minister Yuan Yong the Prince of Gaoyang.

Erzhu, under suggestion of his general Gao Huan, toyed with the idea of taking the throne himself or offering it to his close associate Yuan Tianmu (元天穆), a distant relative of Emperor Xiaozhuang.

Erzhu therefore stopped these plans and offered a deep apology to Emperor Xiaozhuang, claiming that the massacre was a result of the soldiers going out of control.

It was not until Erzhu offered offices to the heirs of the officials who died and publicly renounced the idea of moving the capital that the people began to return to Luoyang.

Meanwhile, Erzhu proceeded to try to reunify the empire, which had been largely divided by agrarian rebellions that rose during the reign of Emperor Xiaoming.

At that time, the more major rebels included: Erzhu's first target was Ge, who had put the important city Yecheng under siege and was getting close to the Yellow River.

Xing was captured and executed in summer 529, but Chen and Yuan Hao, who declared himself the emperor of Northern Wei upon entering Northern Wei territory, took the opportunity to capture Yingyang (滎陽, in modern Zhengzhou, Henan), defeating Yuan Tianmu as he returned from the campaign against Xing, and approached Luoyang.

Emperor Xiaozhuang decided to flee Luoyang, and he crossed the Yellow River to rendezvous with Erzhu Rong and Yuan Tianmu at Zhangzi (長子, in modern Changzhi, Shanxi).

He then captured Moqi's capital Gaoping (高平, in modern Guyuan, Ningxia), capturing Moqi's general Xiao Baoyin—a former major Northern Wei general and Southern Qi prince who had, during Emperor Xiaoming's reign, unsuccessfully tried to reestablish Southern Qi.

Soon thereafter, Erzhu Rong's generals Hou Yuan (侯淵) and Liu Lingzhu defeated and killed Han Lou, and the empire became basically reunified.

Emperor Xiaozhuang also feared a repeat of the Heyin Massacre, and therefore engaged his officials Yang Kan (楊侃) and Yuan Luo (元羅) in the conspiracy as well.

The populace of Luoyang expected that either Erzhu Rong would carry out a coup or Emperor Xiaozhuang would act against him, and many fled.

When Erzhu arrived at the capital, however, he entered the palace with minimal guards and without weapons, and so Emperor Xiaozhuang considered not acting against him.

Yuan Hui, however, persuaded Emperor Xiaozhuang that even if Erzhu Rong was not planning a coup, that he still should not be allowed to be left alive.

Emperor Xiaozhuang was imprisoned in a Buddhist temple in Jinyang, and 10 days after he left Luoyang, Erzhu Zhao had him strangled.