The 31 year-old actress told E! Online that the quirky Jess is "kind of like a 13-year-old".
"I think Jess as a person, and the way that her personality is, has some of myself and especially some of my younger self," she suggested. "[She resembles] my 13-year-old self."
Deschanel added that Jess will explore her lost youth after she is dumped by her long-term boyfriend.
"I have to find a new support system, so I'm basically living my 20s as I approach my 30s," she explained.
The star also ruled out the possibility of her sister, Bones star Emily Deschanel, appearing on New Girl in the near future.
"There's no immediate plans to [have her on the show]," she said. "She's really busy and she's eight months pregnant."
She added: "[Emily] has her own show to shoot, so I think she has to make sure she shoots that first! But we would love to have her if she ever had a spare moment."
New Girl premieres on Tuesday, September 20, at 9/8c on Fox.
> Justin Long joins Zooey Deschanel's New Girl
Watch a trailer for New Girl below: