Abstract: In automatic question and answering system，traditional way of the answer extraction depends on participle of answer fragment and the accuracy of semantic comprehension from the context，which consumes manpower and time during the extraction process． To solve the above problems，the approach of step answer extraction is adopted where the final answer extraction is conducted through the extracted answers from the sentences． The model of answer sentence extraction is built in combination of Bi-LSTM ( Bi-directional Long Short-Term Memory) and Max Pooling during the extraction process． The experimental results show that the MＲＲ ( Mean Average Precision) index of this model is close to 0． 75 in the extraction of the answer sentence．

Key words: Chinese question answering system, answer sentence extraction, bi-directional long short-term memory ( Bi-LSTM)