Once considered to be of Christian origin because of its obvious references to Christ, ten fragments of The Book of Enoch have been found at Qumran in the Dead Sea Scrolls, it is known to have existed in its present form since at least the 2nd Century BC.
It is considered an apocryphal book as well as a part of the Pseudepigrapha (literally means “falsely ascribed” is a collection of works supposedly written by a biblical character), although it is not a part of the canonical Apocrypha.
The Book of Enoch is considered to have been written by Enoch, the seventh from Adam.
The book was believed to have been composed by Enoch, the great-grandfather of Noah.
It is generally believed that the Apostles and the writers of the New Testament were fully aware of the Book of Enoch also called 1 Enoch.
Most critics and scholars believe it was begun in the second century BC and was a collection of works that includes writings for the first century BC as well.
The only thing we know for certain is that fragments of the book date back to the 2nd century BC.
Some believe it contains the actual words of Enoch and that it was handed down through the ages.
There is no real way to know for certain if that is so.