Song Dynasty was a developing period for coins in Chinese history, and the coins of song dynasty are of great importance in coinage history. By analysis and comparison of coins from North and South Dynasty, alloy compositions and mintage techniques were studies, which gives some information about scientific techniques and social economic forms them. In the mean time the analytical data also provide basis for conservation. X-ray photography, XRD , XRF, metallography were used for analyzing 21 coins of North Song and 21 coins of South Song Dynasty. The results show that all these coins are mainly coined with Cu, Sn, Pb. The coin compositions of North Song are more stable and rational, whereas those of South Song are dispersive containing high Pb content. The alloy qualities of South Song coins are not as good as those of North Song and in poorer conservation state.