In generally large-scale and strong distributed P2P systems, updates issued by replicas may be delayed, and then resource location performance on the Internet may be depressed. According to the characteristics of updates about key-attributes in P2P systems, an optimistic data consistency maintenance algorithm is proposed. The update about key-attributes was separated from user update request, and based on classifying key-update conflicts, a double-level mechanism including preprocessing buffer and key-update table were applied to detect and reconcile conflicts, and then conflicts were solved by policies as last-writer-win and divide-and-rule. Delaying key-attributes updates cannot occur by the optimistic disposal method, and then it cannot depress efficiency of resource location based on key-attributes, which adapts well to P2P systems for Internet. The simulation results show that it is an effective optimistic data consistency algorithm, achieving good consistency overhead, resource location and resource access overhead, and having strong robustness.