Abstract: This paper discusses the distribution of fractures in West Kunlun and the contact relation between Tarim Block and Tibetan Plateau by using magnetic data. And the authors concluded that Kogan fracture is not truncated by the NE Kizilto-Koslap fracture, but it prevents the Kizilto-Koslap fracture from extenting to northwest. The authors also discussed the relationship between Tarim Block and Tibetan Plateau by 2.5 D professional inversion software. The results shows that the bidirectional subduction mode is supported by the magnetic data.