The 43-year-old actor said he is already tensed about the trouble she might bring home when she begins going out with boys, reported People Magazine.
"It's coming, and I'm nervous about it. Having two boys and a girl, I realise that boys take trouble to other people's houses, and girls bring it home.
"So, the thing we are struggling with is the rules, and setting fair rules for the boys and for Willow, but she's not having any of that," he said.
Smith said he still has a plan for how to deal with his daughter's suitors.
"When Willow does bring a boy home, I'm going to screen him and find out everything about him. And that's going to happen when she's 40, when she's allowed to go on dates!"