In this work, copper core yarn (cotton sheath) was made into a plain fabric and treated with nanosilver particles. Copper (diameter 0.09 mm) was used as core material for producing Dref II core yarn with resultant count of 295 tex and core/sheath ratio 16/84. The cotton material is used as sheath. The Dref II friction spinning was used to produce the copper core yarn. In order to improve the electromagnetic shielding effectiveness of copper core yarn woven fabrics by nanosilver finishing, the copper core yarn (cotton sheath) was made into a plain fabric and treated by nanosilver particles with various levels of concentration, temperature, and curing time through Box-Behnken design. The electromagnetic shielding effectiveness values for different applying conditions were measured and analyzed, and are discussed in this paper.