Objective To investigate the deviation of the film drawn by rubber rollers in automatic bag making machine.Methods The stress, deformation and displacement of the film were calculated based on the explicit dynamic analysis of the towing apparatus using the FEM method. Results The results showed that both the nonparallelism of the rollers and the inhomogeneity of the friction coefficients between the film and roller could cause the film deviation. The film skewed to the side of larger gap between the rollers, or to the side of smaller friction coefficient. Conclusion In comparison, the nonparallelism of the rollers was more important to the film deviation. When the height difference between the ends of the central axis h was 0. 5 mm, the film deviation could reach almost 2 mm at the initial moment, and the deviation increased nonlinearly as the time increased.