An eco-friendly Zn(O,S) film with a wider band gap is emerging as one of the promising Cd-free replacement material, which can be deposited by radio frequency sputtering. The effect of sputtering pressure on the Zn(O,S) films properties and the devices performance are studied systematically. At high pressure, the ZnS phase is found in the Zn(O,S) films resulting in a higher barrier at Zn(O,S) /CIGS interface which would lead to a low recombination activation energy (Ea). By reducing sputtering pressure, single phase of Zn(O,S) films are conducive to carrier transport as well as promote the films electric properties, ultimately improving the performance of Zn(O,S)/CIGS solar cells.