Crystalline CaSnO3·Ca2SnO4 composite oxide was prepared by wet-chemical route and the electrochemical properties as anode material for lithium ion batteries were studied. The average size of crystal CaSnO3 is 11.2nm and the average size of Ca2SnO4 is 9.6nm. The particle size of CaSnO3·Ca2SnO4 composite oxide is 100-200 nm with aggregation in 750℃. But on the inside of the composite oxide, the sample breaks up to small particle about 33 nm. The reversible capacity of the sample is 678 mAh/g in the first cycle and the average decay of charge capacity is 1.37% per cycle after 20 cycles. The observed capacity involved in the first discharge and the reversible capacity during subsequent charge-discharge cycles shows that the electrochemical process in CaSnO3 is similar to other Sn-based oxide materials, namely, an initial structural reduction with Sn-metal formation followed by reversible Li-Sn alloy formation.