Abstract: Aimed at the blowout accident under complex landform, five obstacle models with different slope were set including twenty degree, thirty degree, forty degree and fifty degree in order to study the spread regularity of the H₂S. Computational Fluid Dynamics(CFD) software Fluent was used for the simulation of H₂S diffusion. Then the concentration values of H₂S about the windward side and the leeward side under the condition of wind were obtained from results of the simulation. The results show the obstacle models with different slop have different influence to H₂S spread when H₂S diffused to stable state. First, the concentration of H₂S will increase on the ground as the slope becomes steeper no matter at the windward or leeward side. Second, the concentration of H₂S at the windward side has a larger difference compared with the leeward side. The results of the simulation provide some guidance about the diffusion regularity of H₂S at the complex landform and the selection of the location about the well site.