Abstract: Three methods of Bjerrum′s formation function, including direct calculation formation function, piecewise fitting formation function and semi-integer formation function, were applied to the determination of stability constants of 8 complexes of neutral amino acids and copper, including serine, alanine, threonine, proline, methionine, leucine, valine and phenylalanine. Hydrogen ion selective electrode was used as indicator electrode, and sodium hydroxide solution was used as titrant. The results obtained were in conformity with those reported in literature.