The main arch of a long-span arch bridge is a compression member. The static wind loads on the bridge not only causes changes of dynamic characters, but also leads the structure to collapse or buckling. Especially, when the arch bridge has longer span and less lateral braces,its stability is much different from the long span cable-stayed bridges and suspension bridges. This paper takes Chongqing Caiyuanba Yangzi River Bridge as a typical example and conducted the wind section tunnel tests. The displacement response of the bridge is obtained and its yield and static stability mechanism under static wind is analyzed. The results show that those factors, such as initial attack angle of the static wind, material yield strength and the static forces coefficients, have great effects on the aerostatics stability of a long span half-through arch bridge.