Abstract: Fluorospectrophotometry was applied to the study the interaction between m-nitroaniline and bovine serum albumin. The maximum quenching effect between m-nitroaniline and bovine serum albumin occurred in Tris-HCl buffer solutions of pH 7.50 after reacting for 30 min. The optimum excitation and emission wavelength were 280 nm and 342 nm respectively. The binding constants at 289,304,318 K were found to be 1.667×104,1.428×104,1.250×104L·mol-1 respectively. Base on the force of interaction between the molecules and correlation among the thermodynamic parameters,as well as the values of ΔH (<0) and ΔS (>0) of the interaction between m-nitroaniline and bovine serum albumin,it was deduced that the force of the reaction was mainly due to electrostatic force. It was found that the fluorescence quenching mechanism was static quenching,which was further confirmed by ultraviolet absorption spectrometry.