[Objective] To clarify the relationship between magnetic susceptibility and climatic factors is the key to applying magnetic susceptibility to inversion of paleoenvironmental evolution. Therefore the study on magnetic properties of the modern topsoil is one of the effective means to establish the relationship between climate and magnetic susceptibility. As far little has been reported in the literature on magnetic properties of surface rock in West Sichuan, and the research in this field will sure help provide a theoretical basis for inversion of paleoclimate and establishment of climate models for the region. [Method] This study was oriented to analyze variation of the topsoil magnetic properties of the region and its influencing factors and mechanism and to explore relationships between the topsoil magnetic properties and environmental factors by taking into account the environmental information, so as to provide scientific data for the study on paleosol and paleoclimate of the West Sichuan leoss region, through analysis of topsoil samples for room temperature magnetism and high temperature magnetism. [Result] The magnetic hysteresis loop shows that the ferrimagnetic mineral low in coercivity was the dominaral magnetic mineral in the soil sample, while M-T curve analysis shows that ferrimagnetic mineral was, in addition to a small amount of magnetite hematite and weakly magnetic hematite, and some lepidocrocite in quite a number of the samples. [Conclusion](1) The fine-grained superparamagnetic (SP) and single domain (SD) ferromagnetic minerals formed during in-situ pedogenic processes in the topsoil of West Sichuan is the dominant factor leading to higher magnetic susceptibility. The mechanism for magnetic enhancement of the topsoil in this area is similar to that in the Loess Plateau. (2) In terms of spatial distribution, the western and southern parts of the West Sichuan Plateau are higher than the eastern and northern parts in magnetic mineral content and in SP and SD particle content, too. Pedogenesis is the strongest in the western part of the Chengdu Plain, where the SP content is higher and the magnetic particles in the topsoil lower in average particle size than those all the other parts of the region. In addition, the topsoil in the area contains relatively more magnetic minerals high in coercivity, which demonstrates that the process of strongly magnetic minerals converting to weakly magnetic minerals did once occur. (3) The influence of climatic factors (especially precipitation) soil magnetic properties is the highest. Through the exploration of topsoil magnetic parameters and climatic factors in West Sichuan, it is found that in the region where the mean annual precipitation (MAP) varies in the range of 600~1000 mm, ?_lf andχ _fdis positively related with MAP in a whole and so are the magnetic parameters, i.e. χ _fd%/HIRM, ARM/HIRM, χ_ARM /SIRM in rainfall interval, but the correlation coefficients of these magnetic parameters with MAP are lower than those in the Loess Plateau, which may be attributed to the complex topography and relatively humid soil forming conditions in the study area.