Introduction. The effectiveness of flax cultivation largely depends on the degree of mechanization of harvesting processes. At the same time, a high productivity of flax stem pick-ups with minimal product losses can be ensured only when working on straight flax stem strips.Aim of the Study. The study is aimed at improving the quality of spreading flax stem strips when performing machine harvesting.Materials and Methods. To achieve this goal, a new device has been developed for controlled spreading of flax stem strips. The working space of the device is formed by the active side edge of a flat belt with protrusions and a clamping mechanism consisting of rods pivotally fixed to each other with the possibility of lifting their clamping surfaces under the influence of a moving layer of flax stems. To evaluate the effectiveness of an innovative technical solution, the proposed device is mounted on an OKP-1.5K turner and tested under production conditions.Results. It has been found that the absence of controlled tracking of the mass of flax stems during spreading generates irregular curvature of the flax stem strip in the frequency range from ɷср = 0,512 to ɷср = 0,712 m–1. The expansion of the frequency spectrum occurred as a result of the effects of wind and machine vibrations on the dried mass of flax stems, with retaining a slight straightness of the flax stem strip at a level of only 45%. At the same time, the use of a new spreading device completely protects the spreading process from these influences and retains the straightness of the treated flax stem strips more effectively (at the level of 73%). In this case, the appearance of new low-frequency oscillations is caused only by the trajectory of the pick-up turner.Discussion Conclusions. The impact of the new spreading device on retaining the straightness of flax stem strips is positive that will ensure an increase in the productivity of flax pick-ups, a proportional reduction in operating costs per unit of operation and reduce the production costs.