本研究以風洞實驗的方式探討均勻流中三維圓柱體的表面風壓分佈。實驗條件採用光滑圓柱體與兩種不同粗糙度的圓柱體，實驗中使用電子式壓力掃描器，同時量測多個位置的瞬時風壓。由實驗數據可以推求得知圓柱體表面的平均壓力、擾動壓力與分離點位置。實驗結果得知：在均勻流場中，平滑圓柱體所受之阻力係數為0.63，小於邊界層流中的阻力係數；平滑圓柱體之擾動壓力不會隨高度上升而有所改變；隨著粗糙程度的增加，圓柱體的分離點會向迎風面方向移動，而分離點移動範圍則會減小。均勻流場的分離點發生的位置較邊界層流的位置靠近背風面，而移動的範圍亦較小。本研究的結果可幫助瞭解在均勻流場中三維圓柱體於不同粗糙程度之表面壓力分佈，與分離點的移動情況。 This study experimentally investigates the pressure distribution on the surface of three-dimensional circular cylinder in a uniform flow. The experiments were carried out in a wind tunnel. The flow conditions include three different kinds of surface roughness. Instantaneous fluctuating wind pressures were measured by an electronic pressure scanner. Based on the pressure measurement, the distributions of mean pressure coefficient Cp, rms Cprms, and peak pressure Cpp were calculated. Also, the separation point and the location of minimum negative pressure will move toward upstream direction as surface roughness increase. Compared to the results of Lee (2002), the moving range of separation point will decrease as surface roughness increase. The experimental results also revealed that the probability of pressure fluctuations for positive pressure is close to the Gaussian distribution function. On the other hand, negative pressure side was skewed and did not necessary follow Gaussian distribution.