Zhuge Liang told Liu Bei that this seal was strong and fierce, and it was difficult to control after the change of the world. In other words, after Liu Bei's death, Feng was not suppressed by anyone. But also attaches great importance to the power of Liu Feng, so once Liu Bei dies, it will inevitably lead to chaos in Shu Han. These are all things that Liu Bei didn't want to see, so he chose to kill Liu Feng. Because this is also to ensure that the son can succeed smoothly.

In fact, Liu Bei didn't want to kill Liu Feng from the beginning, and he always wanted to reuse Liu Feng. This is mainly because Meng Da surrendered to Wei under pressure at that time, but Liu Feng did not surrender to Wei. In addition, Liu Feng is a general who can fight, so it can be said that he has always been recognized by Liu Bei. In addition, Liu Feng is his adopted son. He has always had very deep feelings and been loyal to himself for so many years, so Liu Bei didn't want to kill him.

But Liu Bei listened to Zhuge Liang and finally made up his mind to kill him. Because at that time, in order to fight for power and profit, brothers would fight to the death, not to mention this kind of relationship. And Liu Chan's ability is far less than Liu Feng. So when Liu Bei died, he was unable to manage Liu Feng. Once there is a contradiction, it will bring great disaster to the whole Shu Han. This also goes against Liu Bei's wishes, so he will listen to Zhuge Liang and kill Liu Feng.

Of course, you can also see the background of that era. Liu Bei's strength has been gradually weakened, because Liu Bei had already thrown Jingzhou away, so Liu Bei was unable to defeat Cao Cao.