关键词: 搜索引擎，元搜索引擎，排序

Abstract: The key technology of meta search engine is ranking algorithm. Based on the research of ranking algorithms,we establish a reasonable mathematical model to describe basic methods of ranking algorithms for meta search engine through a series of steps including simplification. By combining with market shares and search results of each search engine, we then propose a new ranking algorithm which is simple and easy to implement

Key words: Temporal expression, Rule, Time expression type, Maximum entropy model,Natural language processing