According to Sheriff Leo Mioduszewski, the 37-year-old Farwell resident phoned in the threat Friday to the Beal City School in Nottawa Township.
Authorities said the woman is the mother of a former student. The sheriff's office said the suspect told school personnel she was going to "level the building."
The school immediately went into lockdown.
The woman was arrested and taken to the Isabella County Jail to await arraignment.