A field trial was carried out at Field Crops Research Station of General Board of Agricultural Research, Abu-Ghraib in spring and autumn seasons in 2013, Six inbred lines of maize (Zea mays L.) were used in this study (gotten it from same station) (Sxn.2 ، zm-9، Am-65، ART-A.2، ART-C-19، syn-35), These inbred lines of maize were entered in half diallel cross in spring season 2013 to produce 15 F1crosses. The seeds of crosses were sown in fall season using R.C.B.D. with three replicates to analyses general and specific combining abilities and to estimate the effects and estimation of some genetic parameters using the approach of Griffing method 4 with fixed model for number days of sowing to 50% (day), plant height(cm), ear height(cm), and rows number per ear, kernels number per row, ear length(cm), 250-kernel weight(gm) and grain yield per plant(gm), Statistics analysis showed that there were found highly significant differences among diallel crosses for all studied characters except 250-kernel weight(gm) in case of SCA, Value of mean square of general combining ability were more than value of mean square of specific combining ability in all studied characters. The values of the variance component specific combining ability were more than that the variance component of general combining ability and the variance ratio 0f GCA to SCA was less than one in all studied characters, The values of the dominance genetic variance more than that the additive genetic variance for all studied characters except 250-kernel weight(gm). Broad sense heritability was high for all studied characters, while narrow sense heritability was low for all studied characters; the value of average dominance degree was more than one for all studied characters.