A method for edge-forming cellulose products in a forming mould system, and a forming mould system (S), where the forming mould system is adapted for forming the cellulose products from an air-formed cellulose blank structure (2). The forming mould system comprises a first mould part (3) and a second mould part (4) arranged for cooperating with each other. The first mould part comprises an edge-forming device (5) with a protruding element (5a) configured for compacting and separating fibres of the cellulose blank structure. The edge-forming device is movably arranged in relation to a base structure (3a) of the first mould part, and the edge-forming device is adapted for interacting with a pressure member (6) arranged in the base structure. The method comprises the steps: providing the air-formed cellulose blank structure, and arranging the cellulose blank structure between the first mould part and the second mould part; forming a compacted edge structure of the cellulose products by separating fibres of the cellulose blank structure with the protruding element, applying an edge-forming temperature onto the cellulose blank structure, and compacting the cellulose blank structure by applying an edge-forming pressure by means of the pressure member onto the cellulose blank structure between the protruding element and the second mould part.