Prepositional phrase (PP) consists of two parts which are a preposition as the leading part and a word or phrase as the tail part. In accordance with this fact, this paper proposes a new approach for identifying PP. In this method, PP identification is transformed into the collocation identification of preposition itself and the right boundary word. The Cascaded Conditional Random Fields (CCRFs) is used in this approach. With the Penn Chinese Treebank 5.1 as our experiment corpus, the F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> rises to 94.63%. This approach obtains breakthrough in this specific field as the current F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> is about 8.6% higher than any publicly published paper.