Police believe 40-year-old Alison Easton killed 10-year-old Alex Corchis and six-year-old Katie Corchis before taking her own life last Monday in Stittsville, Ont.
They called it a "horrific" double murder and suicide.
No details about the cause of death have been released.
Police say Easton was involved in the local neighbourhood watch program, and a neighbour described the stay-at home mom as "very quiet."
The funeral is being held at All Saints Anglican Church at 11 a.m.