Abstract: Theneedforaccurate quantita tive analysisofcompoundaminopyrineinjectionhasengendered the development of a ne w assay proced u re for the three i ndi vid ual medicamen ts of thisformulationbystatistical simulation(also styled Monte Carlo)spectrophotometry that has beenreported previously.It is well known that the absorbance- concentration relationship of a chemical component maydeviate from Beer'slaw , and errors of measurement propagate and multiply in mathematicaloperations. But there are difficulties in carrying out experiments on large systems of comp onents toascertain the real relationship and a new ul traviolet and visi ble absorpti on spectrophotometry——statistical simulation spectrophotometry( SSS for short)---has been developedfor the assay ofmedicaments in compound formulations. The key step of SSS isto build a medel which provides thenumerical imitation of the sum-up absorbance- concentration relationship of the real dosage form atseveral sensitive wavelengths, and the method of stepwise regression hasbeen used in this research thathas satisfactorily extended SSS to the quantitative analysis of a three- medicament compoundformulation ,compoundaminopyrine injection. SSS is accurate , rapid and practicable ,and promiseswell to be adopted as an official assay method for compound formulations.