Abstract: To extract the data of product specification in B2B system,the ruled string extracting method based on dou-ble-array trie was proposed.The data feature is formed as "name:value" for the parameters of the product specification in B2B system．The method constructs the rule according to the data feature of specification parameters．The double-array trie is generated for the extracting processing according to the rules database．The optimization measures are adopted to improve the storing efficiency for the double-array trie．The measures include giving high priority to handle the sub tree with more child node．The method can extract all the ruled string by scanning the input text data once．The accuracy of the extracting results is improved via filtering according to the restrictions condition of the rules．Experimental results show that the extracting method can improve accuracy and decrease complexity comparing to the traditional method．The complexity of the extracting algorithm is O(n).

Key words: Double-array Trie,Vertical search,Rules string,B2B system