The 'Call My Name' singer has allegedly agreed with her former partner's lawyers to write just four pages about their marriage, which came to an end in 2010 following repeated accusations about his infidelity.
She will not expose any information that is not already in the public domain and his representatives will read through the book before its release in October, according to The People.
"Cheryl won't be writing much at all about her marriage," an insider said. "She will be penning her opinions about her and Ashley but there will be no more sordid revelations.
"Her fans might have been hoping for some real fireworks and her laying into Ashley but it won't be happening.
"The fact that there will be little focus on Ashley doesn't mean the book won't be a brilliant, entertaining read. It will be Cheryl's life, from her tough upbringing to her global fame."
However, the source insisted that Cole's former X Factor boss Simon Cowell - who was said to have been "mesmerised" by the Girls Aloud star in his own tell-all book - will feature heavily in the autobiography.
"There is no way that Simon will come out of this unscathed," they said. "He's fair game to Cheryl after what he allowed to be written about her."
Cole previously played down how much of her book will be focused on Cowell, saying: "I don't know if I've got 300 words to say on Simon. He might get a footnote if he's lucky."