Gravity casting experiments were carried out using A356 aluminum alloy. Based on the experimental results, the Interfacial Heat Transfer Coefficient (IHTC) between the casting and metal mold was identified by using the method of inverse analysis combined numerical simulation and optimization. The variation relation of calculated IHTC with interfacial temperature was discussed. The results show that an obvious change for IHTC can be seen when interfacial temperature is at 545~555 ℃ and whereas it remains at a constant value liquidus and under 545 ℃. The IHTC value is about 3 000 W?m-2?K-1 over solidus curve and about 500 W?m-2?K-1 under 545 ℃ respectively. And the approximate mathematics model was also established by the linear regression analysis. The model of IHTC is a function with the change of interfacial temperature between the casting and metal mold. In addition, a good agreement was obtained between the simulated and experimental temperatures by applying the identified IHTC，so that the inverse analysis method could be verified to be available and accurate.