Influence of ceramsite on mechanical properties of bonding interface between steam cured concrete（SC）-self-compacting concrete（SCC） was investigated by splitting test. The results show that addition of ceramsite can improve splitting tensile strength of bonding interface， increase bonding interface opening displacement value and thus significantly increase ductility of bonding interface. Stress-strain curves of bonding interface can be divided into linear development stage， plastic development stage and failure stage. The two-parameter Weibull distribution model can better simulate the rising section of stress-strain curves of bonding interface， and when the amount of ceramsite is less than 4 kg/m²， the evolution process of damage variable can be reduced with increasing ceramsite content.