Tension control method for coating thin film

The invention provides a thin film tension control method in a process of coating a thin film, in particular relates to a tension control method for secondly coating a thin film with fragile material coated on a single face. By the non-coating side of a thin film of a negative pressure adsorption plate 4, the negative pressure adsorption plate 4 produces adsorptive force, so that the thin film between a pull roll 10 and the negative pressure adsorption plate 4 forms tension. The coating traction tension is matched with the thin film unreeling tension control, and a coating material 8 is coated by a coating roll 7 and a lower roll 6 on the side where the thin film 2 contacts with coating roll 7. The tension control method for coating a thin film provided by the invention ensures the tension to be stable in the coating process to obtain the coating quality of the coating, and avoids the destruction or detachment of the coating caused by contact and extrusion of the exiting coating in a traditional tension adjus