The formation mechanisms of moral risk in unified planning fund of outpatient service of new countryside cooperative medical service is analyzed using the asymmetry theory of economics information.It is suggested that the particularity of social system of medical care insurance gives a huge activity space to moral risk, which has deteriorated under the current mode of paying according to item, the mode has also resulted in the irrationality growth of medical expenses.The paper then put, forward proposals for the improvement of fund disbursement and supporting measures.