Nine genotypes of pea (Pisum sativum L.) were crossed in half diallel design to study heterosis, nature of gene action and heritability for earliness and yield components traits. Mean squares of genotypes were found to be highly significant for all studied traits, providing evidence for presence of considerable amount of genetic variation among studied genotypes. The results showed that the majority of crosses exhibited significant heterosis estimates over mid and best parents for all studied traits. The results indicated that the magnitude of additive genetic variance (σ2A) were positive and higher than those of non-additive (σ2D) one for all of studied traits, indicating that additive gene action played a major role in the inheritance of pea. The broad sense heritability values were 98.89 and 97.84% for days to flowering and number of branches per plant, respectively. While, the narrow sense estimates were 83.10 and 85.27%, for the same traits, respectively. For yield and its component traits the results showed that the estimated values of broad sense heritability were ranged from 96.30% for 100 seeds weight to 99.89% for fresh pods weight per plant. In the same time, the estimates of narrow sense heritability ranged from 64.90% to 91.83% for 100- seeds weight and number of pods per plant, respectively.