The effect of the thickness of strips and cooling rates on the macro- and micro-structural features such as grain size, secondary dendrite arm spacing, and intermetallic phases, were studied for AA6111 aluminum alloy cast on a simulator of a horizontal single belt strip casting process. Different strips were investigated. As strip thickness decreased from 2.49 mm to 0.55 mm, the grain size decreased about 56% and secondary dendrite arm spacing decreased about 56.7%. An equation was developed based on the results obtained via thermal analysis which relates secondary dendrite arm spacing to cooling rate in this process. The formation and behavior of various complex intermetallic compounds in AA6111 were studied using scanning electron microscopy. The compositions of the precipitates were analyzed using electron probe microanalysis and their most likely stoichiometries determined.