Abstract: A tree structure algorithm based on vertical tid-list to resolve the frequent itemsets program in Apriori is put forward.The algorithm combines the ordinal character of itemsets and makes the nodes ascending order by support count in the tree，so the sets of the candidate frequent itemsets is the least totally.The algorithm can greatly reduce the candidate frequent itemsets，keep the completion of frequent itemsets，reduce the cost of computing，and improve the efficiency of algorithm.

摘要： 针对Apriori寻找频繁项集问题，提出了基于垂直事务列表的树形结构的挖掘算法。该算法结合项集的有序特性，使生成树的每一层结点从左往右按支持度大小升序排列，这样得到的候选频繁项集的集合是最小的，大大减少了候选频繁项集的数量，而且能保持频繁项集的完整性，从而节约了计算开销，提高了算法的效率。