The production of high quality and quantity of natural silk depends mainly on the nutritional status of the mulberry leaves fed to silkworms so, the healthy growth of silkworms and subsequently the economic traits are influenced largely by improving the mulberry leaf quality and feed efficiency of silkworm. The present study was an attempt to assess the effect of four extracts of Euphorbia tirucalli plant; acetone, petroleum-ether, ethyl alcohol and aqueous extracts on the biological characters, cocoon parameters and silk characters of the mulberry silkworm, Bombyx mori; the plant powder was soaked in petroleum-ether, acetone, ethyl alcohol and water serially. Each extract was used with three concentrations (2.5, 1.25 and 0.625 %) added to mulberry leaves. The schedule of application was applied since the beginning of the 5^th instar (every day first feed). Most concentrations of botanical extracts of Euphorbia tirucalli especially the concentrations (2.5% and 1.25%) increased significantly biological and technological characters of B. mori compared with the control group; larvae reared on mulberry leaves enriched with these concentrations of extracts especially acetone and aqueous extracts showed a significant increase in larval weight, cocooning percentage, emergence percentage, fecundity and pupal weight compared with the control, while, no significant differences were observed among means of the treatments in fertility percentage. On the same pattern, cocoon aspects (cocoon weight and cocoon shell weight) and silk characters (filament length, weight and size) enhanced significantly by rearing silkworms on fortified leaves with botanical extracts concentrations, compared with the control. While no significant variation was noticed among the means of silk ratio (%). Conclusively, fortification of mulberry leaves with acetone, petroleum-ether, ethyl alcohol and aqueous extracts of E. tirucalli plant as nutritional additives improved the biotechnological characters of mulberry silkworm B. mori especially the acetone and aqueous extracts with increasing the concentrations.