Abstract: The experiments for selecting optimum analytical parameters of simultaneous determination of twelve elements, i.e.Si, Mn, P, V, Ti, Cu, Co, Ni, Cr, Mo, Mg, Al in carbon steel and low-alloy steel were carried out using new type(IRIS/HR)plasma optical spectrometer.The effects of analytical spectral line, back ground correcting point, high frequence power, carrier gas pressure, flow rate of liquid sample and auxiliary gas on analytical results were investigated.The analytical parameters selected are used for analyzing standard sample.The results obtained show that the features of this method are simple, rapid and accurate.