The present study was carried out at Sakha Agric. Exp. Station Res. during the three successive seasons 2010, 2011 and 2012. The objective of this study to estimate of some genetic parameters to understand the inheritance of yield and its components of cotton crosses (Giza 90 x pima s⁶) and (Giza 88 x Australian).The experiment was grown in a randomized complete blocks design with three replication. The means of the six populations; P_1, P₂, F₁, F₂, Bc₁ and Bc₂ of two cotton crosses recorded for boll weight, seed cotton yield, lint cotton yield , lint percentage, micronaire reading, fiber strength, fiber length and uniformity ratio were subjected to scaling test and six population method to detect epistasis and estimates of m, d, h, i, j and L parameters. The results indicated that the additive dominance model was adequate to demonstrate the genetic variation and its important in the inheritance of most studied traits non allelic interaction was operating in the control of genetic variation in most studied traits. The additive gene effect, wee significant for quality traits in two crosses, while the dominance were significant for seed cotton yield, lint yield and lint percentage.