The main systematic and random errors of atomic emission spectral analysis and various procedures used for their reduction are considered: classical internal standard approach, non-spectral matrix effects, the use of several spectral lines of the analyte and internal standard with and without weight coefficients, signal drift, instability of sample injection and conditions of spectra excitation. The necessity of incorporating those methods into the software of the devices intended for atomic emission spectral analysis with various sources of spectrum excitation, including inductively coupled plasma is demonstrated. An algorithm and stand-alone program for optimization of the calibration curve based on multiline recording of the spectral lines of matrix elements and analyte, internal standards, solvent, and discharge atmosphere, capable of implementing the above methods of error reduction both in calibration and analysis are developed.