Abstract: XML query optimization has become a hot and difficult research topic.This paper presents a model of XQO for XML query optimization，which combine the query processing，illustrating and designing XQO from several optimizing query parse：Logical optimization、physical optimization，query execution.At last，through the experimental data to validate XQO，which can effectively reduce the cost of practical execution and improve querying speed.

摘要： XML现有的查询技术不够成熟，效率低下，精确度不高，如何优化查询成为业界热点和难点问题。结合当今查询优化算法技术，设计了一个查询优化模型XQO，从查询过程的各个阶段进行优化查询解析、逻辑优化、物理优化，设计执行策略和算法，并从实验结果验证优化的效果。