Crystal structure, magnetic and transport properties of Sr2-xGdxFeMoO6 (0 <= x <= 0.25) are investigated. The anti-site defect in this series can be adjusted by rare-earth element of Gd. Gd3+ replace for Sr2+ results in the increase of anti-site defect due to the differences in valence and size between Gd3+ and Sr2+. The moment of Gd3+ may be in canted structure. The effective moment of Gd3+ is about 1.5 mu(B)/Gd3+, which is anti-parallel to that of Fe3+. The moment of Gd3+, Fe3+, and Mo5+/Mo4+ interact each other, and play important roles on transport and magnetic properties. (C) 2010 Elsevier B.V. All rights reserved.