Understanding the question is the key point in the question answering system. Therefore, this paper designs a multi attention layer model, extracts some missing features from the storage module, and uses Gru unit to organize them reasonably. By using non-linear operations to combine the results of different attention layers, we can avoid extracting only the linear combination of memory modules. Effectively combine the process of problem understanding, including the classification of problem words, the vocabulary annotation of problem sentences, the identification of problem sentence patterns, the classification of problems and the identification of problem centers, the grammatical analysis of question sentences and the identification of question sentence patterns, so as to achieve problem understanding. Experimental results show that this method improves the accuracy of problem understanding.