Abstract: The GSM module SIM900A was controlled by Arduion microcontroller to implement remote security monitoring under the overpass water depth in the form of sort message. The Water Level Monitoring and Alarming System consisted of the Arduino microcontroller, water level monitoring module, LED display warning module, GSM remote alarm module. HC-SR04 ultrasonic rangefinder was used to detect the water level. The LED would flash and alarming when the water was over cordon, at the same time, the GSM module given remote alarming in the form of SMS short message. Relevant staff would take measures to dispose when he receipted the information. After many experiments, the testing results showed that the System was accurate and reliable.