The invention discloses a laser monitoring and alarming system for deep foundation pit displacement. The laser monitoring and alarming system comprises a laser monitoring system, wherein the laser monitoring system is connected with a processing system, and the processing system is connected with an automatic alarming system. According to the abovementioned scheme, the laser monitoring and alarming system has the beneficial effects of simple structure and rational design, and can be used for overcoming operation and judgment errors caused by subjective factors and objective factors of a person, monitoring in real time around the clock, monitoring alarming fault affected by subjective reasons and objective reasons can be monitored, and finding out potential safety hazards immediately and sending an alarm within the shortest time.