Abstract: OBJECTIVE To investigate the interactions of salicylic acid and bovine serum albumin (BSA) in the presence of Cu²⁺. METHODS The interaction between salicylic acid and BSA was investigated using fluorescence at different temperatures. The effect of Cu²⁺ on the salicylic acid-BSA system was also researched. RESULTS The quenching constants, binding constants and binding force type were measured according to theory model. CONCLUSION The presence of Cu²⁺ doesn’t change quenching type and force type between salicylic acid and BSA, but the apparent association constant(KLB) becomes higher.