Abstract: A dual- wavelength linear regression spectrophotometry has been intro-duced and evaluated. Depending on a group of standard mixture solutions the optimalwavelengths and calibration curve can be determined simultaneously by linear regressionmethod. The deviation of absorption resulting from molecular interaction can be calibratedby this method and the results are more accurate. The validity of this method has been con-firmed through its use in the analysis of compound injection of antipyrine with satisfactoryrecoveries. Results obtained by Kalman filtering (KF), partial least squares (PLS)and tar-get factor analysis (TFA)are also given.