The invention relates to a method and a device for producing Lyocell fibres which are extruded from a cellulose solution of water, cellulose and tertiary amine oxide in a spinning head (25). The cellulose solution is obtained in a number of process steps directly from the cellulose (3, 4) or with the formation of a cellulose suspension. Since the degree of polymerisation decreases in the course of processing the cellulose through to its extrusion in the cellulose solution, with the processing of celluloses with a low degree of polymerisation there is the risk that the endless moulded bodies (2) extruded in the spinning head (25) exhibit defective quality. In order to also be able to process celluloses (3, 4) with a low degree of polymerisation without having to accept reduced quality, according to the invention, the residence time of the cellulose from its introduction into the device (1) through to the extrusion of the cellulose (3, 4) in the cellulose solution is set in dependence of the degree of polymerisation of the cellulose, of the cellulose suspension and/or of the cellulose solution.