Method for surface treatment within an air-jet spinning device, which comprises - a yarn take-off channel traversing a spinning cone and having an outlet for withdrawing a spinning yarn from the air-jet spinning device, - a spinning housing arranged at a distance from the spinning cone and enclosing the spinning cone, and - a nozzle device which can be supplied with compressed air for generating an air flow circulating the spinning cone in an envelope gap between the spinning cone and the spinning housing, characterised in that, during a spinning process or an interruption of the spinning process, - a fluid is supplied to the outlet on the outlet side or introduced into the outlet, the fluid being a cleaning fluid with an effect of cleaning the surfaces inside the air-jet spinning device or being an additive with an effect of influencing the fibre or the fibre or yarn property, directly or indirectly via an effect that influences the surfaces inside the air-jet spinning device as needed, and - temporally before, during or after the presentation or introduction of the fluid by means of the nozzle device, an air flow is generated that circulates around the spinning cone in the envelope gap, whereby the fluid supplied to or introduced into the outlet passes via the outlet of the yarn take-off channel into the air-jet spinning device in order to effect a treatment of the surface of the air-jet spinning device. - a yarn take-off channel traversing a spinning cone and having an outlet for withdrawing a spinning yarn from the air-jet spinning device, - a spinning housing arranged at a distance from the spinning cone and enclosing the spinning cone, and - a nozzle device which can be supplied with compressed air for generating an air flow circulating the spinning cone in an envelope gap between the spinning cone and the spinning housing, during a spinning process or an interruption of the spinning process, - a fluid is supplied to the outlet on the outlet side or introduced into the outlet, the fluid being a cleaning fluid with an effect of cleaning the surfaces inside the air-jet spinning device or being an additive with an effect of influencing the fibre or the fibre or yarn property, directly or indirectly via an effect that influences the surfaces inside the air-jet spinning device as needed, and - temporally before, during or after the presentation or introduction of the fluid by means of the nozzle device, an air flow is generated that circulates around the spinning cone in the envelope gap, - a fluid is supplied to the outlet on the outlet side or introduced into the outlet, the fluid being a cleaning fluid with an effect of cleaning the surfaces inside the air-jet spinning device or being an additive with an effect of influencing the fibre or the fibre or yarn property, directly or indirectly via an effect that influences the surfaces inside the air-jet spinning device as needed, and - temporally before, during or after the presentation or introduction of the fluid by means of the nozzle device, an air flow is generated that circulates around the spinning cone in the envelope gap, whereby the fluid supplied to or introduced into the outlet passes via the outlet of the yarn take-off channel into the air-jet spinning device in order to effect a treatment of the surface of the air-jet spinning device.