Diamond-coated drawing dies are considered as the next generation of drawing dies for their unique characteristics, such as high hardness, wear resistance, low friction and thermal conductivity in the cold drawing process. In order to utilize the superior characteristics of diamond coatings toward improving the drawing performance, modified typed drawing die is developed to minimize the diameter shrinkage. Finite element model simulation is used to simulate the low carbon steel tube sinking drawing process, using a two-dimensional axi-symmetric elastic–plastic element model. The parameters of tube drawing die, such as the main reduction zone α ₁, the semi-angle of the secondary reduction zone α ₂ and the length of the secondary reduction zone L, are considered. Based on the simulation results, the cause of diameter shrinkage is studied. The influence of parameters of tube drawing dies on the diameter shrinkage is investigated using the response surface methodology. The gained equation reveals that L is the most significant parameter.