A flame simulator of an electric fireplace, including: a light source (1); a flame board (3); a flame projection screen (4); and a rotary drum (2); wherein the light source (1) is provided in the rotary drum (2); the rotary drum (2) is transparent and a light-concentrating block (20) is provided on a surface thereof; a flame pattern (31) is provided on the flame board (3); light concentrated by the light-concentrating block (20) is projected onto the flame board (3) and reflected by the flame board (3) to the flame projection screen (4) for forming a flame image. The flame is bright and has a sufficient dynamic effect. The rotary drum (2) and the light-concentrating block (20) can be made by injection molding for a simple structure and convenient production.