[7] Like his brothers, Sima Gan was given various posts and titles during the Cao Wei era; unlike them, Gan's posts and titles were largely minor or ceremonial.
In June 260, Cao Mao launched a coup in an attempt to seize back power from Sima Zhao.
Sima Gan was then made Prince of Pingyuan, with a fiefdom of 11,300 households.
Although his fiefdom was large, he did not take an active role in administration; instead, he appointed officials based on their abilities and the positions which needed to be filled.
Gan then said, "You must not emulate the son of that Bai woman (referring to Sima Lun)."
At the time, people could not understand his actions; they thought that Gan was ill, or that he had turned reclusive.