The NiFe/FeMn bilayers with different buffer layers (Ta or Ta /Cu) and Ta cover layers were prepared by magnetron sputtering. The results showed that the exchange bias field of NiFe/FeMn films with the Ta buffer was higher than that of the films with the Ta/ Cu buffer .We investigated the crystallographic texture, surface roughness and surface segregation, and demonstrated that the decrease of the exchange coupling field was caused by the Cu surface segregation in NiFe/FeMn films with Ta/ Cu buffer layers.