A step die made of H13 steel was utilized in this investigation cast aluminum alloy AA6061 at a pressure of 95 MPa in sections measuring 3 mm, 6 mm, 9 mm, 12 mm, and 15 mm in thickness. Surface temperatures during the squeeze casting process, as well as temperatures at distances of 3 mm, 6 mm, and 9 mm from the inner wall of the die, were recorded using K-type thermocouples. Utilizing the inverse method to solve 1-D heat conduction equations, we successfully determined the interfacial heat transferring coefficients (IHTC) and the interfacial heat flux (IHF) of the cast and die surface. The calculations revealed that with the commencement of squeeze casting, there was a significant rise in the IHTC for each of the five sectional steps. These IHTC reached their peak before they began to decline. The peak range of IHTC incrementally increased with the section thickness, from the 3 mm of Step 1 up to the 15 mm of Step 5. Moreover, the rate at which the IHTC reached its peak and then stabilized at a low level was slower for steps with greater thicknesses.