The authors try to transform dependency tree into phrase structure tree, and detect annotation errors automatically based on manual rules. The method has been used in processing Peking University Multi-view Chinese Treebank (PMT). Although PMT has been manually checked twice before processed by this method, 1529 errors were detected among the 50275 sentences and the precision is 100%. The errors mainly belong to three types: word segmentation error, mismatching between POS and syntactic role, and syntactic role error. This method can further improve treebank quality, and be applied to other dependency treebanks.