This review represent plants genetic diversity (PDG) generally in crop plant and especially in Barley (Hordeum vulgare), can be studied (PDG) and stored as a (PGR) plant genetic resources as gene bank , DNA library for saved genetic material at long time and crops improvement can be utilized in breeding programs strategies in future. In this study observed the significance of plant genetic diversity (PGD) and (PGR) especially on agriculturally important crops , analysis of plant genomic using molecular markers. Barley is a well important studies crops using as a model for study genetic plant, cultivated barley Hordeum vulgare easily hybridization by genetic fingerprinting with wiled barley Hordeum spontaneum. The molecular markers showed their relation with locus of geographic factors and imposed stresses. Here, discussed barley genomic through relationship between genotype and phenotype traits using molecular markers useful for genetic physiological maps construction.