The invention discloses a method and system for transmitting voice by an intelligent pendant. The method comprises following steps: A, detecting the actual noise value of a current environment by the intelligent pendant, comparing the actual noise value with a preset noise threshold value, when the actual noise value is more than the noise threshold value, entering to the step B, when the actual noise value is less than or equal to the noise threshold value, entering to the step C; B, setting the microphone on the back of the intelligent pendant as the microphone for collecting voice, transmitting the collected voice data to a mobile terminal; C, setting the microphone in the front of the intelligent pendant as the microphone for collecting the voice, and transmitting the collected voice data to the mobile terminal. According to the invention, the pendant with the microphones is used for intelligently detecting and judging the noise conditions of the surroundings; when the noise is excessive, the microphone close to the chest is switched and activated; the voice is transmitted by using the chest sound, therefore the surrounding noise is eliminated, and the call quality is promoted.