Secondary Data Processing deals the information further by re-crawling and categories based on the basic of structured data. It is the key researching module of Vertical Search Engines. This paper introduces an application model of vertical search engine briefly and proposes an improved classification algorithm for the categories to enhance the advantage of vertical search engines. The algorithm achieves the responsiveness and the accuracy of vertical search by reducing the time complexity and accelerating the speed of classification. This paper proved the improved algorithm has the better feasibility and robustness when it’s used in secondary structured data processing based on vertical search engines.