Abstract: A system and method for ambient monitoring temperature and humidity, includes a controller, a host and an alarm device. The controller includes a sensing module and a determining module. The sensing module senses temperature and humidity. The determining module determines whether the sensed environment temperature and humidity are abnormal according to predetermined standards, and determines howl long the environment continues to be abnormal, and outputs an abnormal signal if the abnormal environment continues to be abnormal beyond a preset time limit. The host is connected to the controller, to transmit an alarm signal according to the abnormal signal. The alarm device is connected to the host, to activate according to the alarm signal.