In this study, we investigated the characters of residues in IDPs that involved in the interations with other proteins. Firstly, 109 IDPs' chains and 299 IDPs-protein compounds which meet the requirement in database were selected; secondly, 4 822 interface amino acid residues which involving in interaction were extracted from the totally 50 031 amino acid residues in the 109 IDPs chains. The results indicated that the 20 amino acids have different propensities when forming IDPs-protein's interfaces. Therefore, we divided the 20 amino acids into three parts based on their propensities: propensity amino acids (ILE, LEU, ARG, PHE, TYR, MET, TRP), middle amino acids (GLN, GLU, THR, LYS, VAL, ASP, HIS) and non-propensity amino acids(PRO, SER, GLY, ALA, ASN, CYS). Moreover, the results show that the 20 amino acids have different propensities in IDPs' different regions (ordered or disordered regions). For example, TRP, LEU, ILE and CYS are more frequently observed compared with ordered and disordered regions. However, there are no obvious difference for GLU, PHE, HIS and ALA residues between ordered regions and disordered regions. Besides, the amino acids which have larger hydrophobicity, polarizability, side chain's volume, solvent accessible surface area, smaller polarity and net charge index of side chain tend to be IDPs-Protein's interface. The results obtained by principal components analysis showed that the polarizability, side chain's volume and solvent accessible surface area of residues had more affect on the IDPs-Protein's interaction residues.