An information extraction method for extracting dynamic information is provided. The method includes using a plurality of information extractors extracting reference values corresponding to the dynamic information from a plurality of information sources, and determining a most reliable value corresponding to the dynamic information based on the reference values. The method further includes determining whether each of the information extractors is abnormal according to the most reliable value and removing the information extractors determined as abnormal. The method further includes rebuilding new information extractors for replacing the removed information extractors. In such a way, reliable dynamic information can be extracted and the information extractors can be maintained for normal operation.