Effect of rare earth alloy modification on properties and microstructure of high carbon equivalent gray cast iron was investigated.The experimental results show that in the way of mechanical property,when the addition of rare earth alloy is 0.2% and 0.3%,the tensile strength of cast iron increases.In the way of microstructure,the addition of rare earth alloy increases the number of primary austenite dendrites,reduces secondary dendritic arm spacing,and changes the eutectic size and quantity.When rare earth alloy is added into gray cast iron,the morphology and quantity of graphite play a major role on the improvement of tensile strength. Effect of rare earth alloy modification on properties and microstructure of high carbon equivalent gray cast iron was investigated. The experimental results show that in the way of mechanical property, when the addition of rare earth alloy is 0.2% and 0.3%, the tensile strength of cast iron increases.In the way of microstructure, the addition of rare earth alloy increases the number of primary austenite dendrites, reduces secondary dendritic arm spacing, and changes the eutectic size and quantity .When rare earth alloy is added into gray cast iron, the morphology and quantity of graphite play a major role on the improvement of tensile strength.