The fritillaria imperialis L plant with Persian names of Mary's tears or Kaiser's crown belongs to Lilies family and Fririllaria genus. This plant is Iran native and is dispersed in Zagros height such as mountains located in Isfahan, Chaharmahal Bakhtiari and Fars province. This plant health benefit has not been investigated completely yet, so that information about it is related to researchers' assessment in so much time ago. Its bulb is used as digester stimulant and emollient. Fritillaria imperialis bulb is stiff swelling softener and their cutter erosion. It is useful to soothe chest pain and toothache. Brewed flower of this plant is used to soothe menstrual pains. And they believe it is a useful drug to eliminate thirst disease, it is also used for Lung discomfort and is used to treat angina, cough relief, asthma, bronchitis and scrofula, backache, and sciatica. According to the studies to locate and select Fritillaria imperialis habitat, pastures bid valley of Frieden County in the west of Isfahan province was selected as one of the most important habitats to grow Fritillaria imperialis. For this purpose, 10 bases were collected, that samples were milled after washing and drying. In continue, this plant essence was extracted by distillation method with stem and then was isolated and was analyzed by mass spectrometer gas chromatography device (GC/Mass). The results showed that the major components in the four organs of bulb, stem, leaf, and flower (blossom), aromatic hydrocarbons, alkanes, and alkaloids were the most constitutive chemical compounds of Fritillaria imperialis essence. Based on the importance of nano-particles biological synthesis, using the bulb, foliage (stems and leaves), and flower the silver nanoparticles were synthesized. Also, silver nano-particles formation was confirmed by XRD, FE - SEM, TEM, UV-Vis, FT-IR, and DLS tests. The average size of silver nanoparticles for three organs of bulb, foliage, and flower was calculated between 30-50 nono-meters. Also, the antibacterial activity of these silver nanoparticles against Staphylococcus aureus and Bacillus cereus (as gram-positive bacteria) and Escherichia coli and Salmonella typhimurium (as gram-negative bacteria) bacteria were investigated by disc publishing method, minimum bactericidal concentration (MBC), and minimum inhibitory concentration (MIC). The results show that the antibacterial activity of synthesized silver nanoparticles using three organs of the bulb, foliage, and flower of Fritillaria imperialis herbal extract is stronger than silver nitrate as positive control against all tested bacteria. Also, the minimum inhibitory concentration and minimum bactericidal concentration of silver nanoparticles were calculated against the mentioned bacteria. Keywords : Green synthesis, Antibacterial activity, mass spectrometer gas chromatography (GC/Mass), Fritillaria imperialis, silver nanoparticles