In 2011-2015 and 2017, we collected wild soybean genetic resources in the northwestern regions including Gansu, Ningxia, Shannxi and eastern Inner Mongolia of China in cooperation with the work of the ‘Northwest Stress-Resistance Crop Germplasm Collection Project’ from Ministry of Science and Technology of the People?s Republic of China. The collecting activies were carried out all over 173 village or sites in 134 township areas of 54 cities or counties, and collected 222 wild soybean accessions (from 220 populations). Fifteen drought-resistant plants were identified from two polulations. The altitudes of collecting sites were 332?1623m and approximately 70% of collected accessions grew over 1000 metres above sea level. Electrophoresis of 13544 plants for Kunitz inhibitoing protein (KTI) showed an 83.90% frequency for Tia type and a 16.69% for Tib type, discovered two new variants Til and Tim, and recognized a rare Tiab1 type. Sequencing analysis revealed that the Til was derived from a mutation Ile→Val at the 57th amino acid in Tibi7 allele, and Tim, from a mutation Arg→Trp at the 159 amino acid, with a synonymous mutation（TTA→CTA）at the 169 amino acid in Tiab1 type，and that 15.76% of Tib electrophoretic type was certified to be controlled by Tibi7 allele. This investigation showed that group ? saponins widely existed in Chinese wid soybeans; however, the northwestern soybeans had a relatively highest proportion of varieties with group ? saponin. Thus far, only Chinese soybeans are found to have group ? saponins, and we therefore proposed a hypothesis that the area of the origin of soybeans may be the Wei-he River Valley, China.