The invention provides a sound recording device comprising a microphone, a sound card, an A/D (analog/digital) converter and a sound processing unit. The microphone is used for acquiring external sound data and transmitting the acquired sound data to the sound card. The A/D converter is used for converting the acquired sound data from an analog form to a digital form. The sound processing unit is used for judging the change of an ambient environment and working out a threshold of the intensity of recorded sound in real time according to the change of the ambient environment so as to remind a person recording the sound when the sound intensity of the person is smaller than the threshold. The invention further provides a method for processing and recording sound by utilizing the sound recording device. According to the invention, the change of the ambient environment can be judged, and the threshold of the intensity of the recorded sound can be worked out in real time according to the change of the ambient environment so as to remind the person recording the sound when the sound intensity of the person is smaller than the threshold.