A privacy film for large-sized displays was designed. Based on the anti-peeping principle of conventional louver type privacy film，a specific light blocking microstructure shape was designed according to the line of sight angle of hume eyes watching different areas of the display，so that the brightness of the whole display area was basically the same when the viewer watched in a fixed position. It could solve the problem that the brightness of the edge area was too low when the conventional privacy film was applied to the large-sized display， and did not affect the anti-peeping effect. Visual angle simulation of large-sized privacy film was conducted using LightTools. The results showed that the brightness of the edge area was 94.9% of that of the center area， and the brightness was 159.2% higher than that of the conventional privacy film.