A field experiment was carried out at field of Dept. of Field Crops Science- Coll. of Agric. - Univ. of AL- Anbar during spring and fall seasons 2015, using RCBD in a split-plot arrangement with replicates three, using three different population 66.66, 88.88, 133.33 thousands plant. ha-1 (main plots) and six genotype Babel, Inkath , Rabih , Giza and E22 (sub plots). Values of genetic, environmental variance genetic, phenotypic coefficient variation and heritability of studied traits sorghum were calculated. The highest genetic variation-environmental variation were 13, 11 and 10.1 for number of grains per head, 1000-grains weight of grains and plant growth rate respectively, the highest heritability was for number of grains per head and 1000 grains weight of grains 92.95%, 91.68% respectively. In spring season, the genotype Giza gave mean highest grain yield 6.27 t.ha-1, but in fall season, the results showed that the cultivar Inkath gave mean highest grain yield 7.72 t.ha-1 and gave mean highest for number of grains per head 2810 grain. The population density has significantly of affected, we conclude that most of yield components traits are affecting more by the genetic factor considering number and weight of grains as a criteria in measuring grains production ability of sorghum.