In order to enhance the safety of wind resistant design of buildings, in this paper, based on the numerical simulation of Computational Fluid Dynamics (CFD), a Ward-type tornado generator is established, and the Realizable k-ε turbulence model is used to simulate the tornado field, and the simulation study is conducted to investigate the wind load on the arch roof low-rise building located in the center of the tornado wind field. The wind pressure distribution of arch roof buildings with different sagittal span ratios was analyzed, and the wind pressure distribution law of the arch roof with sagittal span ratio of 1/10 is investigated under vortex ratios of 0.2, 0.5, and 1.5. The results show that: when the building is located in the center of the stationary tornado, the arch roof is subjected to negative pressure under the action of the tornado, and the wind pressure is centrosymmetrically distributed; with the increase of the vector-span ratio the increase of wind pressure on the arch roof is not obvious; at the same time, the vortex in the center of the top of the building separates and transfers to the eaves of the two sides, and the number of vortices on the roof decreases; with the increase of the vortex ratio, the wind pressure on the roof of the arch low-rise building in the central part of the tornado wind field increases firstly and then decreases.