The invention relates to the technical field of smartphones, in particular to a method, a device and a system for biological information identification and alarm based on social software. The method comprises the following steps of S1.setting and storing biological identification information and rescue information of a friend of the social software corresponding to the biological identification information on a mobile terminal; S2.detecting whether a user inputs the biological information identification in a standby state; S3.when the user inputs the biological identification information, comparing with the stored biological identification information; and S4.when comparison is successful, sending the rescue information to the friend of the social software. According to the method and the device, the rescue information is sent to the friend of the social software in a silent manner through biometric feature recognition, the information sending has lower requirement for a network signal than communication, and the delay can be carried out at short time, so that the possibility of sending the rescue signal is greatly increased; in addition, the user can set a plurality of social software and friends to send the rescue information, so that the flexibility for sending the rescue signal is greatly increased; and lastly, the rescue information and feedback information are both sent in a silent manner by the software, so that the user safety is greatly protected.