More than 20 years ago, Xiao Dazong had a childhood girlfriend. She went to college and went to the city. He went to see her alone, but was refused. As soon as they quarreled, he accidentally killed her. Later, he fled south to the ancient city. In 2006, he saw Yin Lu standing naked in Han Tianlin's studio and decided that she was not a good girl. He killed Yin Lu while Han Tianlin took his daughter to see a doctor. Later, Han Tianlin and Tian Wen disposed of the body privately, which led to a series of subsequent events.

Since Lianzhou entered the ancient city for love, Xiao Lao has been the closest person to Lianzhou. He listened to Lianzhou's complaints as an elder and enlightened him. At the beginning of Lian Zhou's pursuit, he deliberately revealed Xiaomi's strange behavior to Lian Zhou, distracting Lian Zhou's sight. Later, relying on himself as Lian Zhou's most trusted person, he continued to commit crimes with the latest clues.