A float switch capable of actively giving an alarm and a monitoring method therefor, said float switch comprising: an alarm device, a switch control device, and a general control circuit embedded in the switch control device; a circuit board capable of actively giving an alarm is embedded in the float switch, and sends, when a water level reaches an alarm water level during power failure and main pump damage, alarm information by means of a client such as a mobile phone app which is used along with the float switch, achieving the effects of emergency disaster avoiding and avoiding a greater economic loss of a user. The float switch capable of actively giving an alarm and the monitoring method therefor provide the ability of actively giving an alarm when the water level exceeds the maximum water level, having high reliability, being able to increase the user experience, being easy to use.