Abstract: In recent years,with the development of mobile communication and information technology,more and more ultra-short text data with a length of no more than 20 words and no auxiliary tag information need to be processed on the network and in actual application scenarios. Because of inherent ambiguity and feature sparseness of ultra-short text,obvious lack of context,and difficulty in distinguishing semantics,an effective classification method is needed in the field of text categorization. To solve the performance problem of those classifiers based on the traditional short text classification method KNN and the decision tree,a new method was proposed based on deep random forest for the classification of commodity short texts. Using a "diversion" strategy and taking an external knowledge base as assistance,the method was arranged to directly determine the commodity name with the clear category in the knowledge base,and to vectorize the description of the incapable extracted commodity name based on a Word2vec tool. And then the vectors in the external knowledge base were classified according to deep random forest. Finally,the classifier was continually optimized until the threshold of training set size was reached. The experimental results show that compared with the traditional classification method KNN and decision tree,the classification method proposed in this paper can improve the average accuracy by 22.78% and 17.22%,and the average recall rate by 22.85% and 15.23% respectively.