Ji-li's dad is stubborn, noble, and proud, the kind of guy who sticks to his principles even when no one else thinks he should. Perhaps that's why he's a thorn in the Red Guards' side. He won't confess to something he didn't do, and he knows he did nothing wrong.
That said, Ji-li's dad presents a softer side to his family. Ji-li tells us that as an actor, he always played "the vicious landlord, the foolish king. But at home he was our humorous, kind, and wise Dad. He loved reading, and he loved including the whole family in his discoveries" (1.56). Aw. Ji-li's dad's a teddy bear when it comes to his three kids.
Ji-li loves her dad very much and definitely feels like she owes him her loyalty when he's arrested (more on this over on Ji-li's page). That doesn't mean she doesn't question him at times, though. Since it's his father who was the rich landlord that's causing Ji-li's family so much trouble now, Ji-li's struggle with feeling torn between family and politics is very much centered around her father. Ultimately, though, her dad's honorable demeanor convinces her to stick by him. She knows he's a good guy, and this doesn't change just because he's locked up.