The embodiment of the invention provides a lexicon updating method and device. The method comprises the following steps that: forming a training sample set by a plurality of general knowledge statement samples and a plurality of specific field statement samples to carry out training on a classification model, and obtaining a word set formed by words independently corresponding to each training sample on the output side of the classification model; on the basis of the classification result of each training sample, determining the contribution weight of each word in the word set for the classification accuracy of the classification model, and selecting X words with a highest contribution degree for the classification accuracy of the classification model from the contribution weights; independently carrying out pronunciation similarity calculation on selected X words and M words with the highest word frequency, and determining a hot word lexicon corresponding to the X words according to a comparison result of a pronunciation similarity and a preset threshold value; and according to comparison result of a spelling similarity and the preset threshold value, selecting hot words which belong to the specific field from the X words to form the hot word lexicon, and adding the hot word lexicon into an original identification lexicon so as to improve an identification effect for words in a specific field application scene.