With XML becoming the de facto standard for representing and exchanging data on the Internet, the problem of validation of XML data when updated has attracted more and more attentions. The traditional brute-force validation processes the entire updated XML document from scratch, which is less efficient. This paper presents a method for XML incremental validation based on simplified XML element sequence pattern, ensuring the XML document to remain conforming to the constrains established by XML Schema. The incremental method focuses on the fragment that the update operations directly affected and thus is more efficient compared to the traditional methods.