The invention discloses a voice wake-up method and device, wherein the voice wake-up method comprises the following steps: S1, acquiring a wake-up word, generating a junk word, which meets the preset condition, according to the wake-up word, and establishing a recognition network according to the wake-up word and the junk word; S2, acquiring voice information, which is inputted by a user, segmenting the voice information into a plurality of voice frames, and extracting acoustic features in each voice frame; S3, sequentially conducting likelihood computation on the acoustic features according to an acoustic model of a convolutional neural network to obtain the acoustic feature score of each acoustic feature; S4, selecting an optimal identification path from the recognition network according to the acoustic feature scores, and considering a voice result corresponding to the optimal identification path as an identification result; and S5, calculating the confidence corresponding to the identification result according to the identification result, and acquiring the wake-up result according to the confidence and outputting the wake-up result. The voice wake-up method and device, disclosed by the embodiment of the invention, have the advantages that the calculated amount is small, the power consumption is low, the false alarm rate of voice wake-up can be reduced, and the user's experiment is improved.