We report magnetic behaviors in Pr 0.7 Sr 0.3 MnO 3 (PSMO) layer grown on charge-ordered La 0.5 Ca 0.5 MnO 3 (LCMO) layer. PSMO/LCMO bilayer film was prepared by pulsed laser deposition on SrTiO 3 (001) substrate. Large particulates at the surface of PSMO layer impart inhomogeneous composition in film, resulting in the variation of film's crystalline structure. We find an exchange bias (EB) in the bilayer film with relative roughness and inhomogeneous surface, whereas smooth and homogeneous surface does not lead to an EB effect. It is believed that an antiferromagnetic structure is formed in the inhomogeneous PSMO layer, which causes the EB effect in this system. The present results are discussed and possible explanations are provided based on the random-field model of EB and the related research results.