The invention discloses a system and a method of intelligently monitoring a dangerous rock collapse and a rockfall hazard. The system comprises a falling rock intercepting sensing system, a signal transmission system and a rockfall hazard information processing center, wherein the falling rock intercepting sensing system is composed of multiple sub falling rock intercepting sensing system; each sub falling rock intercepting sensing system is composed of a rock intercepting net device and a signal acquisition and analysis device fixed on the rock intercepting net device; the signal acquisition and analysis device can acquire vibration information of the rock intercepting net and the information is transmitted to the rockfall hazard information processing center via the signal transmission system; the server of the rockfall hazard information processing center can judge whether the vibration is from a falling rock according to features of the signal and whether to send warning information is thus judged. The system has the advantages of accurate monitored data, high system operation reliability and low error rate. The method provided by the invention is realized according to the system. Thus, intelligent and real-time monitoring on the dangerous rock collapse and the rockfall hazard can be realized.