Abstract: Clear G-bands which were closely adjacent,multiple and distributed along thechromosomes were showed in the mitotic metaphase chromosomes of Psophocarpustetragonolobus (L.) DC by the advanced ASG method. The karyotype and G-banding patterns were analysed. Its karyotype formula is 2n= 18= 4m + 14sm (2SAT), and karyotype asymmetry belongs to 2 B type. The number,position of distribution,staining de-gree of G-bands between homologous chromosomes are basically identical; but nonhomologous chromosomes are distinct in G-band patterns. So chromosome pairing for karyotype analysis could be carried out more accurately and nonhomologous chromosomescould be distinguished easily. The application of the advanced ASGmethod in karyotype analysis and G-banding and the polymorphisms of G-band patterns are discussed.