This investigation carried out to determine combining ability and types of gene action for yield component traits and some fiber properties in cotton. The genetic materials in this investigation included six cotton varieties i.e. G.85 (P₁) ; Kar. (P₂) ; G.93 (P₃); Pima S7 (P₄) Aust.12 (P₅) and G.86 (P6). All these varieties belong to the species Gossypium Barbadense L. and they were utilized in a trialed crosses mating design to produce 60 hybrids. In 2013 growing season all genotypes which included 60 genotypes were evaluated at the Agriculture experimental Station at Sakha using a RCBD with three replications. the following traits were estimated : boll weight, seed cotton yield per plant, lint cotton yield per plant, lint percentage, number of bolls per plant, seed index, fiber fineness, fiber strength, Upper half mean and uniformity ratio %. The results indicated that the mean squares of genotypes were highly significant for all studied traits. The results also showed that the performances of most the three way crosses were as good as or better than their both grand parents or / and their third parent. From the analysis of triallel crosses the results illustrated that the variety G.86 (P6) was a good combiner as a parent and / or grand parent for most of studied traits and Kar. (P2)  and G.93 (P3)  were good combiners for most of studied fiber properties. In general, the crosses (Kar. X Aust. 12) x G.93, (Kar. X Pima S7) x G.93, (G.85 x Pima S7) x Kar., (Kar. X Pima S7) x Aust. 12, (Kar. X G.93) x G.85, (G.85 x Pima S7) x Kar., (G.85 x Pima S7) x G.86, (Kar. X G.86) x Aust.12, (G.93 x Pima S7) x Aust. 12, (Pima S7 x G.86) x G.85, (Pima S7 x Aust.12) x Kar. And (G.93 x Pima S7) x Kar., appeared to be the best promising combinations for breeding toward yield and its component traits, which the crosses  (G.85 x Kar.) x G.86, (G.85 x G.93) x Kar., (Pima S7 x G.86) x G.85 and (Aust.12 x G.86) x G.85 would be the best for fiber fineness and (Kar. x G.93) x G.86 appeared to be the best for fiber strength. Most of these combinations had involved at least one of the best general combiners for yield. Which would be utilized in a breeding programs to improve yield traits through the selection in the segregating generations of these crosses. The results indicated that yield components as well as fiber traits were mainly controlled by additive variance and additive x dominance and dominance by dominance epistatic variances. These results also revealed that the calculated values of heritability in broad sense ranged from 77.01% for Upper half mean to 97.38% for lint cotton yield per plant. In the same time the heritability in narrow sense ranged from 3.63% for seed index to 37.79% fiber strength.