Abstract: A method for preparing a graphene film with a micrometer groove array and a triangular cross-section includes the following steps: A, subjecting a flexible sheet material to a pre-treatment, and obtaining a flexible sheet substrate; B, coating a carbon precursor material onto the flexible sheet substrate according to a required thickness of a solid carbon precursor, and conducting curing to obtain a flexible composite film loaded with the solid carbon precursor; where the carbon precursor material has a triazine ring network cross-linking structure; and C, adjusting laser parameters, and conducting direct-writing scanning on a surface of the solid carbon precursor with laser, followed by cleaning and drying to obtain the graphene film with a micrometer groove array and a triangular cross-section. The method solves the problems of current traditional processing techniques, which struggle to meet the high precision and three-dimensional requirements of a micro-scale/nano-scale structure of graphene films.