A novel and stable spectra derivative Kalman filter UV spectrophotometric method was proposed, and applied to the simultaneous determination of ternary mixture of phenol, 2-chlorophenol and 2,4 dichlorophenol successfully. The reasons for using spectra derivative is that it contains more information including absorbance and its change with wavelength; the obviously different signals can be caught more conveniently at the position of absorbent overlap. The noise from experiment and the errors from transfer model can be solved by Kalman filter. Calibration set with 30 standard solutions (range of 1-10 mg x L(-1)) and 61 wavelengths (260-290 m, 0.5 nm slit width) was used for each sample. The exact value of absorbance derivative was obtained from regressed simulation for the extended 8th order polynomial, and the standard work matrix of derivative spectra Kalman filter was performed from partial least-squares method. The linear discrete Kalman filter was applied to the test. The recovery experiment showed that the derivative spectra Kalman filter simultaneous determination of mixture for phenol, 2-chlorophenol and 2,4 dichlorophenol is not only exact, but also stable.