In the present mathematical model, the process of film formation from polymer solution is described. Rheological parameters of the model were determined by comparing theoretical curves and experimental data measured for simple shear in chitosan solutions. Dimensionless similarity criteria were found for the rheological characteristics of the process. This work considers the effect of these criteria on the dependence of the velocity, concentration and width of the film on the distance from the exit of the die. Mathematical modeling used in the design and manufacture of products made of polymer materials gives a number of benefits, such as the ability to control the quality of polymer products and to solve a number of production optimization problems. Such problems are based on a mathematical model, which should be fairly simple but reflect all relevant characteristics of the process. The fabrication of polymer films is one of the common processes in polymeric material processing. The process of obtaining films from polymer solution is two-staged and is so complex. This complexity is caused by the fact that an increased polymer concentration results in a sharp increase in the polymer system’s viscosity. Thus, while developing mathematical models to describe the processes of polymeric film formation, the characteristics of each forming step should be considered. The set of dynamics and mass transfer equations is written in a one-dimensional approximation, when the elongation velocity, the concentration of the solvent, and the non-zero components of the stress tensor are functions of the distance to the die exit, and the rheological parameters of the model are known functions of concentration. A set of ordinary differential equations for the dependence of the width and thickness of the film on its longitudinal velocity for the case of uniaxial tension was obtained and solved.