Feeding is a critical aspect in silkworm rearing, as it directly influences its growth, development, and silk production. Glutamine is a building block for making proteins in the body. It's also synthesized other amino acids and glucose. The present study was conducted to evaluate the impact of glutamine powder as protein sources on some the biological and economical characters of mulberry silkworm, Bombyx mori L. It was added to mulberry leaves with different concentrations (1 ,1.5 and 2 g ∕ L water). This experiment was applied from the beginning of the fourth larval instar until hatching egg in spring 2023. The majority of the studied concentrations resulted in a significant improvement in the mulberry silkworm characteristics; the concentration 1g of glutamine showed a significant increase in larval and pupal weight, duration of larval stage, cocoon weight, cocooning percentage, cocoon length and silk ratio when compared with others concentration. Moreover, others concentration of glutamine was more effective than control. Therefore, adding glutamine to the diet of mulberry silkworm larvae B. mori can positively improve biological and economic characteristics. It can improve growth and development (the growth rate, weight gain, overall health of the silkworm larvae and higher Cocoon yield and quality). Finally, glutamine could be prescribed to the breeding programs to achieve high quantity and quality of cocoon yield for silk production.