In order to study the influence of external platform width on wind loads of large-span buildings, wind tunnel tests of six rigid models with various platform widths were carried out. In particular, the characteristics of mean wind pressure coefficient and fluctuating wind pressure coefficient were studied. The test results show that the enlargement of platform widths increases the mean wind loads. The mean wind loads change from small to large and to small again with the increase of platform width. The most unfavorable situation occurs when the platform width is 12 meters, and its growth rate reaches 33%, while its growth rate is 20% when the platform width is 20 meters. Meanwhile, the increase of platform widths increases the fluctuating wind loads. The most unfavorable situation takes place when the platform width is 12 meters, and its growth rate reaches 11%, while its growth rate is 8% when the platform width is 20 meters, and the rate is lower than 5% in other cases. The fluctuating wind loads on the leeward side decrease when the width of platform increases. The maximum decrease reaches 7% when the platform width is 20 meters.