A manufacturing method of an OLED anode and display device are provided, which the former method comprises the steps: forming an anode-film layer, a material is an ITO, on a substrate; forming a photoresist-film layer on the anode-film layer; patterning the photoresist-film layer to acquire a photoresist-mask pattern, which comprises: an area of photoresist full-retention, photoresist half-retention, and a photoresist full-removal, wherein the photoresist area of half-retention is located between the full-retention and the full-removal; etching the anode film layer to acquire an anode pattern; removing the photoresist half-retention area; perform a plasma treatment to a portion of the anode pattern outside the photoresist full-retention area by adopting a first gas, comprising at least one of O2, N2O, CF4, Ar; removing the photoresist-mask pattern. The disclosure increases the small thickness portion of brightness to compensate for the display unevenness caused by the thickness difference and improve the display quality.