Golrokh Ebrahimi Iraee faces years behind bars even though her writing has not been published.
She was convicted of "insulting Islamic sanctities" and "spreading propaganda against the system".
Amnesty International called the conviction "ludicrous" and the trial "farcical".
Victims of stoning are executed by having rocks thrown at them until they are dead. In Iran, most are women accused of adultery.
Ms Ebrahimi Iraee's work describes the emotional reaction of a young woman who watches the film
The Stoning of Soraya M - which tells the true story of a young woman stoned to death - and is so enraged that she burns a copy of the Koran.
The Iranian authorities found the piece on 6 September 2014, when the writer and her activist husband Arash Sadeghi were arrested by men believed to be members of the Revolutionary Guard.