Co/FeMn/Co multilayers were prepared by magnetron sputtering. The change of magnetic moments by insertion of Pt spacer at the Co （bottom）/FeMn interface and FeMn/Co （top） interface has been investigated. According to the hysteresis loops measured by alternating gradient magnetometer （AGM）, the saturation magnetization （Ｍs） of multilayers is changed by the Pt spacer at the Co （bottom）/FeMn interface, and there is an asymptotic approach of Ｍs to the theoretical value of Ｍs of the cobalt bulk of 1440 kA/m as the thickness of Co layer （tCo） is increased. This behavior is due to the production of net magnetic moments at the Co （bottom）/FeMn interface, which are decreased by Pt spacer at the Co （bottom）/FeMn interface. However, a significant difference between the Co （bottom）/FeMn interface and the FeMn/Co （top） interface is observed, as little influence of the Pt spacer on magnetic moments is shown when inserted at the FeMn/Co （top） interface.