The present study was carried out during spring season, 2017 in Sericulture Laboratory Economic Entomology Department Faculty of Agric. Menoufia Univ. The study was conducted to evaluate the effect of light color and exposure time, on some technology and physiology characters of silkworm, Bombyx mori L. Reeled silk filament characters, length (m), weight (g) and size (denier) were measured in the cocoons resulted from silkworm larvae exposed todifferent colors and lighting periods. The highest mean treatment length of reeled silk filament of cocoon spun by B. mori larvae exposed during the 4th instar was (1119.2 m) at green light 24 hr, followed by blue light 12 hr recording (1077.76 m) while green light 12hrrecorded (954.4m, compared to control cocoon (1109.76 m). In addition, statistical analysis of the obtained resultsrevealed that there were significant differences in the prolongation in silk filament length as compared to the control. The highest mean of reeled silk filament weight (0.228 g) was recorded at the cocoons spun by B. mori larvae exposed to green light 24 hr, followed by that exposed to red light 12 hr recording (0.216 g) and blue light 12 hr (0.214 g) compared with (0.232 g) for control. Statistical analysis of the data indicated that there were high significant differences between lights and times in all treatments. The highest mean size of reeled silk filament (2.08 dn) was recorded for the larvae exposed to red light 24 hr, followed by red light 12 hr treatment giving (2.01dn), followed by (1.99 dn) at natural light treatment, and (1.96 dn) which was recorded at blue light 24 hr treatment, compared with control which attained (1.91dn). Data regarding the biochemical analysis of total soluble protein, and protein enzymes (ALT and AST) and total fats in silk gland of silkworm larvae exposed to light and several times. The obtained results are as follow: The total soluble protein content in silk worm larvae silk gland ranged between 1.92 mg/ml for blue light 24 hr, 1.88 mg/ml for red light 12 hr and 1.87 mg/ml for green light 12 hr compared to 1.94 mg/ml for the control larvae for silk gland samples. The total soluble protein content in silk worm larvae blood ranged between 2.68 mg/ml for green light 24 hr, 2.61 mg/ml for blue light 24 hr and 2.67 mg/ml for natural light compared to 2.45 mg/ml for the control larvae for blood samples. The total fats content of silk worm larval silk gland ranged between 139 mg/ml for natural light, 137 mg/ml for red light 24 hr and 131 mg/ml for red light 12 hr compared to 127 mg/ml for the control larvae for silk gland samples. The total soluble fats content in silk worm larvae blood ranged between 114 mg/ml for blue light 24 hr, 107 mg/ml for dark and 90 mg/ml for natural light compared to 98 mg/ml for the control larvae for blood samples. Silk gland activities of glutamic oxaloacetic transaminase (ALT) and Glutamic pyruvic transaminase (AST) enzymes in silk worm were measured.