Abstract: A method and a device for continuous forming of a mat of particle lignocellulosic material by means of a batching unit (12) with a distribution chamber (15) in connection with the manufacture of board. The material is deposited on a continuous forming web (16), and the width of the mat is controlled by means of laterally movable partition walls (30) in the distribution chamber (15). The main part of the material is deposited on the forming web (16) between the partition walls (30), and the partial amount of the particle material dropping outside the partition walls (30) is diverted by means (32) and discharged separately in the distribution chamber (15) and re-used in the mat forming, in that it is directly placed as a surface layer of the mat by distribution means (35).