The effects of stud radius on dimensionless torque and physical properties of the textured yarns in the stud type cone drum twister were studied in this paper. To study the effect of stud radius, theoretical background and experimental results were discussed. It was shown that stud radius was a very important factor in the stud type cone drum texturing device. Besides, an account is taken of an experimental investigation for the physical properties of textured polypropylene yams into the effect of stud radius. It was shown that, as the stud radius increased, the crimp rigidity and the skein shrinkage of textured yarn decreased. As the stud radius increased, the breaking elongation increased.