The purpose of this study was to assess the susceptibility of landslides around the area of Guizhou province based on fuzzy theory. In first instance, slope, elevation, lithology, proximity to tectonic lines, proximity to drainage and annual precipitation were taken as independent, causal factors in this study. A landslide hazard evaluation factor system was established by classifying these factors into more subclasses according to some rules. Secondly, a trapezoidal fuzzy number weighting (TFNW) approach was used to assess the importance of six causal factors to landslides in an ArcGIS environment. Thirdly, a landslide susceptibility map was created based on a weighted linear combination model. According to this susceptibility map, the study area was classified into four categories of landslide susceptibility: low, moderate, high and very high. Finally, in order to verify the results obtained, the susceptibility map and the landslide inventory map were combined in the GIS. In addition, the weighting procedure showed that TFNW is an efficient method for weighting causal landslide factors.