Abstract: Optimized geometries of twelve 99 T c m-N 3S pseudo-peptide complexes,which have been synthesized and labelled with 99 Tc m for further biodistribution study, are obtained by molecular mechanics methods. These complexes are optimized by semi-empirical quantum mechanics method——ZINDO/1 and the electronic structures are calculated.Quantitative structure-activity relationships (QSAR) are investigated by multiple linear regression analysis method. Several equations are obtained which reveal that molecular dipole moment ( μ ) and charge of the complexes are all significant descriptors correlating to renal uptake, and volume of the complexes correlates well with liver uptake.