To investigate the interference of various metal ions existed simultaneously in the determination of chromium in soil，by flame atomic absorption spectrometry，a multi-factor and multi-level experiment was conducted. It was found that in the solution of simple matrix，calcium，magnesium，iron，aluminum，titanium，manganese，vanadium，nickel and cobalt had significant effects on the determination of chromium，which can be eliminated by adding ammonium chloride as a matrix modifier. Depending on the differences of elements and concentration，the effects were also different. However，in the digestion solution of the actual or standard soil samples，there was no significant difference in the determination of chromium due to the complex matrix which can offset each other whether the matrix modifier was added or not. Therefore，soil samples for analysis of chromium can be prepared together with other metal elements (copper，zinc，nickel，lead，cadmium，etc.) without adding matrix modifier in the practical determination.