The influence of graphite morphology on the phase, microstructure and properties of hot dipping and diffusion aluminizing (HDDA) coating on flake/spheroidal graphite cast iron (FC/FCD) was investigated. The microstructure and properties of the HDDA coatings on FC/FCD were determined by the graphite morphology. The outer and inner layers of the HDDA coating comprised the Fe2Al5 and FeAl phases, respectively. The outer layer of HDDA on FCD was dense and uniform; however, some pores of different sizes were found in the outer coating on FC, resulting in looser HDDA coating. Hence, the wear resistance of the HDDA coating on FC was worse than that of the coating on FCD. During oxidation, many continuous oxidation channels were formed from the coating surface to the matrix in the HDDA coating on FC, resulting in the oxidation of graphite in the HDDA coating and the matrix. However, only exposed spheroidal graphite was oxidized in the HDDA coating on FCD. Thus, the high-temperature oxidation resistance of the HDDA coating on FC was also worse than that of the coating on FCD.