It is important to study how male and female grasshoppers respond to topographyinduced environmental changes and to identify dominant topographic factors that affect the spatial distribution. The spatial heterogeneity pattern of male and female grasshoppers responding to terrain reflects the resource co-evolution mechanism that grasshoppers adapt to the diversity of habitats. Through field survey from July to August, 2009, by using the GIS and S-PLUS, we developed a GAM model for Oedaleus asiaticus in the upper reaches of Heihe River on the northern slope of Qilian Mountain. The topographic indices included elevation, direction, slope, position, profile and plane. The results showed that the structure and D₂ values of models were different for male and female, so was the model stability in modeling, indicating their differences in response to the gradients of topographic indices. The gradient analysis in this model showed that male and female were distributed in a wide range of environments, in different gradients of elevation, direction, slope, position, profile and plan, in all land positions. However, this did not mean that the distribution of male and female was equally affected by each factor, or had a uniform distribution probability in the whole environmental range. The GAM modeling results indicated that the distribution of male and female were mainly controlled by the elevation, but the upper limit of elevation for distribution of the female grasshopper was higher than that of the male. On the regional distribution, there was higher abundance of the female in the whole region, but they were mainly located in the region with profile less than 0, and the male mainly concentrated in the south and southwest slopes. The heterogeneity attribute of O. asiaticus in selecting habitats made the spatial pattern of male and female in the same terrain obviously different.