The temperature at specific positions was measured by multi-channel data acquisition system in order to understand the solidification and feeding process of the sample. The Olympus metallurgical microscope was used to observe the macrostructure of the casting and analyze the freezing mechanism. The mold filling and solidification processes of the Al-alloy sample were studied by using the commercialized simulation software Z-Cast. And the simulated result was compared with the results of practical pouring test. When preheat temperature of mold is low, the pouring temperature should be higher in order to ensure completely filling of mold. As a result the solidification of sample could be feeding effectively, and the shrinkage on the upper end of sample could be eliminated. It is shown that the casting simulation software Z-CAST can be used to simulate the filling and solidification process of gravity cast Al alloy and can provide exact flow fields and temperature fields thus can predict cast defects and their positions.