Validity of service in the service system is significantly affected by reliability of providers and availability of service contents. Most service inspiring schemes in pecr-to-pecr （P2P） networks associate each provider with reputation or money to ensure provider＇s reliability so as to improve the availability of service contents. However, these schemes bring considerable risk to consumers when a provider with high reputation or money publishes a malicious service content. Moreover, the number of providers decreases as some providers are rejected while they have unconsciously published one or several polluted content., ever. The risk may spread to more users and cause the collapse of the service system. Recently, some researches have shown that the unconscious polluted contents are over twice as many as the intentional polluted contents. In order to distinguish the unconscious polluled contents from the intentional polluted contents and rescue those correlative users, we propose an audit model based on each service content to improve the validity of services. In our model, each node is associated with money, and each service content is associated with reputation. The unconscious polluted contents are prevented via consumers＇ evaluation, and the intentional polluted cantents and malicious providers are rejected via audit executors＇ evaluation. Simulatinn results show that the model improves the ratio of available service contents and reliable providers.
