Sun Lang, courtesy name Zao'an (早安), was a son of the warlord Sun Jian, who lived in the late Eastern Han Dynasty. He was a half-sibling of the other five known children of Sun Jian, all of whom were born to Sun's first wife Lady Wu.
Sun Lang's misfortune occurred in 222, shortly after Eastern Wu's triumph over Liu Bei at the Battle of Xiaoting. The emperor of Cao Wei, Cao Pi, launched a multi-pronged invasion against Eastern Wu. One prong was led by Cao Xiu, who led his army to Dongkou, which was defended by Lü Fan. Sun Lang was acting in capacity as a guardsman of the palace at the time and thus was under Lü's authority. However, early in the battle, he accidentally set fire to his own camp, destroying a large quantity of supplies in the process. To compound Eastern Wu's difficulty, a freak storm struck at Lü's fleet, sending it crashing along the northern shore. Those troops in Lü Fan's fleet who did not drown were then in danger of either being attacked by Cao Xiu's troops or dying of starvation. Luckily for the Eastern Wu forces, the general Xu Sheng arrived, driving back Cao Xiu's forces long enough for Lü Fan to regroup, and in the end, Cao's fleet was driven back.
Despite the victory, Sun Quan was furious that his half-brother had nearly brought destruction upon the state and he punished Sun Lang heavily. Sun Lang had all his military ranks and appointments stripped off, was disowned from the Sun family and forced to change his name to Ding Lang (丁朗). He spent the rest of his life in prison.
In some versions of Luo Guanzhong's historical novel Romance of the Three Kingdoms, Sun Lang was referred to as "Sun Ren" (孫仁). In the novel, he was born to Lady Wu's fictional younger sister, who was known as Wu Guotai.
- Chen Shou (2002). San Guo Zhi. Yue Lu Shu She. ISBN 7-80665-198-5.
- Lo Kuan-chung; tr. C.H. Brewitt-Taylor (2002). Romance of the Three Kingdoms. Tuttle Publishing. ISBN 0-8048-3467-9.
- de Crespigny, Rafe (1990). Generals of the South: the foundation and early history of the Three Kingdoms state of Wu. The Australian National University, Canberra. ISBN 0-7315-0901-3.