The field experiment was conducted during the winter season of 2022-2023 at the Field Crops Research Station of the College of Agriculture - Tikrit University. The experiment followed a totally randomized block design with three repetitions, organized in split plots. The primary panels consisted of three different concentrations (0, 100, and 200 mg L-1) of compound nano fertilizer, while the subsidiary panels contained additional information. The study examined six different genotypes of flax (Syrian, Sokha 6, Sokha 5, Short 8, Sokha 1, and Polish) to analyze various characteristics such as the duration from planting to 50% flowering, plant height, number of main branches, number of capsules, number of seeds per capsule, weight of 1000 seeds, seed yield, total seed yield, biological yield, harvest index, and oil percentage. Genetic parameters were also estimated for these genotypes. The results for each concentration of the nanocomposite fertilizer can be summarized as follows: The genetic variation values exceeded the environmental variation values for the attributes under study, across all three concentrations of the nano-complex fertilizer. The coefficient of genetic and phenotypic variation for plant height, number of capsules, seed yield per plant, total seed yield, and harvest index showed a moderate value, while the other characteristics exhibited a low value for each fertilizer concentration. The values can be either The heritability in the broad sense exhibited high values for all traits, particularly for the number of capsules per plant and total seed yield. Plant height and weight of 1000 seeds showed a moderate heritability. On the other hand, the biological yield of the plant and the harvest index displayed low heritability for the remaining traits at each concentration of the nano-complex fertilizer.