On his deathbed, Liu Bei said to Zhuge Liang, "Ma Su exaggerates, so he can't use it more." Liu Bei's comments on Ma Su, warning Zhuge Liang and Ma Su are grandiose and beyond his practical ability. Don't entrust him with important tasks, pay more attention to him. Zhuge Liang, on the other hand, didn't think so, which violated Liu Bei's words. After Liu Bei's death, Zhuge Liang appointed Ma Su as the pioneer of the Northern Expedition to Wei State, and gave him a great responsibility. However, because Ma Su violated Zhuge Liang's battle plan, did not listen to other people's advice and went his own way, the war ended in failure. Ma Su was also convicted and beheaded by Zhuge Liang in tears at the age of 39.

Ma Su (190-228), a native of Yicheng, Xiangyang (now the south of Yicheng, Hubei), was the younger brother of Shu and Han generals in the Three Kingdoms period. At the beginning, Liu Bei entered Shu as Jingzhou, and successively served as Mianzhu County Magistrate, Chengdu County Magistrate and Yu Yue Taishou.

Zhuge Liang, the premier of Shu Han, appointed him to join the army. Ma Su is brilliant and good at military planning. Zhuge Liang has always attached great importance to him, every time he meets and talks, from morning till night.

In the 6th year of Jianxing (228), during Zhuge Liang's Northern Expedition, Ma Su disobeyed Zhuge Liang's operational instructions, resulting in the fall of Jieting, and was beheaded by Zhuge Liang after withdrawing troops.