CFD numerical simulation method was employed to study the wind field characteristics of three-dimensional hills under isolated hill and two adjacent hills condition. The influence of the calculation model surface roughness on the wind field was studied. The wind fields on isolated hill with different slopes were calculated. The wind fields of two adjacent hills in left-right arrangement were also investigated, and the influence of the hill slope, wind azimuth and hill distance on the wind field was studied. The results show that, if the model surface roughness increases, the speedup effect of half hill height above the top of the hill decreases and the height of vortex region increases. The speedup effects on the cross-wind plane of an isolated hill are more significant than those on the along-wind plane, and the most unfavorable position ranges from the half hill height to the top of the hill on the cross-wind plane. When two adjacent hills are in left-right arrangement with zero distance, the speedup ratios on the front hill are larger than those on the rear hill under yawed azimuth, and the speedup ratio, when wind blows perpendicularly to the two hills, is between these two data.