Six inbreed lines of maize were used in this study Entered in half–diallel cross program according to a method of griffing. the seeds of parents and crosses were grown in a randomized completely block design R.C.B.D with three replicate, to study the heterosis, combining ability and gene action for the number of days to silking, number of ears per plant, rows number per ear, kernels number per raw, 300 kernels weight and grain yield per plant. Results of Statistically analysis indicated that there were highly significant differences among genotypes means for all studied character results of genetic analysis showed that MSgca and MSsca in diallel for reciprocal crosses were high significant for all studied characters. the result were showed that the cross Zm-5 x Zm-1 gave the highest cross vigor in each grain yield per plant 113.4% and number of days to silking -7.88%. The average degree of dominance was higher the one for all traits indicating the presence of over dominance. The broad sense heritability was high for all studied traits. the variance ratio of GCA to SCA appeared less than one for all characters. All the traits under Additive gene action.