A process for preparing an optical colored polyester film using microwave technique comprises the following steps: microwave dyeing treatment by passing a polyester film through a disperse dye suspension with a steady water phase in a dye-pool comprising a microwave generator; rinsing with water; rinsing with solvent; finally drying treatment, and then uniform optical colored films with various colors are obtained. The optical colored films are used as optical filters or optical protection films and as glass window films for automobile, and domestic and office windows.