Watermelon (citrullus lanatus. Thunb.) is an important vegetable crop grown in Egypt. Studying the genetic behavior of some economical traits is very important to produce local watermelon hybrids. A complete diallel cross mating design using five watermelon varities named as; Giza-1 (1), Giza- 21 (2), Charleston gray (3), Crimson sweet (4) and Dulzero (5) were performed. Different vegetative and earliness traits were studied. These traitswere :plant length in centimeter ,number of leaves per plant, number of branches per plant, fresh weight per plant in grams, dry weight per plant in grams, days to first male flower to first female flower. Different genetic parameter and heritability values as well as correlation among pairs of studied traits were evaluated The caculated means of parental varieties and their hybrids  showed that the average means of the F₁ hybrids, F_1r reciprocal hybrids and overall  F1 hybrids significantly exceeded the mid-parents and some better parent (B.p) The results indicated that the magnitudes of the non-additive genetic variances including dominance were larger than their corresponding estimates of additive genetic variances for all studied traits with few exceptions.The estimated values of heritability in broad sense were larger in magnitudes than their corresponding estimates of heritability in narrow sense for all studied traits.These findings cleard the importance of dominance variances and additive variances although dominance was larger . The results illustrated that both phenotypic and genotypic correlation coefficients values were closed to each other with respect to most pairs of studied traits. It could be also noticed positive genotypic (rg) and phenotypic (rph) correlation and highly significant between (P.L. cm) and (No.L./P.), (No.B./P.), (F.W./P. gs), (D.W./P. gs).