The research was carried out at Tal Hedya Research Center in Aleppo, General Commission for Agriculture Scientific Research (GCSAR), Syria, during 2011 and 2012 seasons. Seven genotypes of cotton were used, and complete diallel hybridization was made to study general and specific combining ability of some productivity traits (sympodial branch number, actual boll number and seed cotton yield). General combining ability (GCA) indicated that the parental genotype Cherpan432 had a high significant GCA for sympodial branch number and actual boll number, but the parents Aleppo118 and Deir El-Zour22 had the high GCA for seed cotton yield. This is a clear indication that these parental genotypes had the largest number of additive genes action, which plays important role in the inheritance of the above-mentioned traits. The estimation of SCA values showed favorite and high significant values in many hybrids resulted from parents, which had highly significant GCA, which means that the gene action type is (additive x additive), and this refers that these hybrids possessing the largest number of additive genes. High heritability broad sense refers to importance of genetic variance in the inheritance of all characters, but heritability in narrow sense values were low in general, indicating the importance of dominance and epistasis genes in the inheritance. According to this result it is recommended to follow the cross method for improvement of the studied traits.