Abstract: On account of dynamic database's characteristic which is changing over time,a new algorithm aiming to mine frequent subtree from dynamic database was proposed. It put forward the support algorithm and subtree-searching space involving some concepts such as tree change probability, subtree expectation support and subtree dynamic support. The problem of mining frequent subtree from dynamic database was investigated. With the process of the subtrecsearching,algorithm definition pruning expressions and mix data structure could reduce subtre}searching space and improve frequcnt subtrec isomorphism speed efficiently. The experimental result showed that the new algorithm is effective and workable and has a better operating efficiency.

Key words: Data mining, Ordered tree, Frecauent subtree, Support, Dynamic database