The invention discloses a voice waking up method and a voice recognition device in man-machine interaction. The voice waking up method includes the following steps: a step of silence detection, performing waking up word detection when a machine detects sound energy, waking up the machine to start voice recognition if the sound energy includes a waking up word, otherwise, enabling image detection; and a step of image detection, waking up the machine to start voice recognition if a man is detected in image detection, otherwise, continuously detecting the sound energy. The voice waking up method and the voice recognition device can achieve natural man-machine interaction by adoption of image detection, and low power consumption can be maintained in a standby state.