Over the last few years, the green synthesis of metal nanoparticles (NPs) has become the center of attention of researchers. There are eco-friendly techniques to determine the properties of metal nanoparticles, produced by microorganisms or their cytoplasmic fluids. In the present study, fungal cytoplasmic fluid of white-rot fungi Phanerochaete chrysosporium ME446 was used for the biosynthesis of Ag NP. The pH value of growing media of fungi, AgNO3 concentration and fungal cytoplasmic fluid of Phanerochaete chrysosporium ME446 (PC-FCF) ratio were optimized to determine the most effective conditions. The formation of Ag NPs was monitored by UV visible spectrophotometer at a wavelength of 420 nm. Synthesized Ag NPs were characterized at scanning electron microscope (SEM). Optimum conditions for the pH value, AgNO3 concentration and PC-FCF ratio were determined as 6.0, 1.50 mM and 100%, respectively. The shape and the sizes of nanoparticles, synthesized at optimum conditions, were confirmed by SEM. The shape was spherical, and the sizes were ranged from 26 to 63 nm