The study aimed to assess the combining ability of six Indonesian tropical maize inbred lines in two different seasons. By using a diallel crossing method, researchers determined the general combining ability (GCA), specific combining ability (SCA), and heterosis of the inbred lines. Results showed that the planting seasons influenced the GCA, SCA, and Reciprocal (REC.) for various yield traits. Non-additive gene action played a significant role in controlling certain traits like ear length and yield. The inbred crosses of G1 x G6, G2 x G5, G4 x G6, and G5 x G6 exhibited the best yields and high heterosis values.