Based on the structural reliability theory, the extreme wind speed forecast method was used to establish the reliability model for analyzing aerostatic instability of long-span suspension bridge. The limit state equation of reliability analysis model is a function of conversion factor, critical wind speed of the aerostatic instability, gust factor and extreme wind speed at the bridge site. In this paper, JC method based on the first order second moment reliability theory was used to calculate reliability indices of the aerostatic instability of the suspension bridge. The results indicate that probability assessment and reliability analysis of aerostatic instability of suspension bridge under stochastic wind loading based on Bayesian theory are more precise and practical, which is more valuable in engineering application.