Abstract: Rational man hypothesis cannot explain the difficulties of collective action and its accomplishment.In the view of institutional economics,the accomplishment of collective action depends on selective incentives and encompassing interest.Ideology is a tool to achieve public interest,it makes people go from individual rationality to collective rationality,but personally,ideology has some irrational features.The evolution of ideology has a feature of Pareto optimization in nature.

Key words: collective action, ideology, collective rationality