The present invention relates to an intellectual surveillance system and a monitoring method thereof. The intellectual surveillance system comprises a camera module and a terminal computer module, wherein the camera module is capable of monitoring and reacting various sudden situations, and then the camera module transmits images and messages of the situations to the terminal computer module through at least one BNC connector and at least one coaxial cable, further that, the terminal module is able to display the images and show a alert so as to complete a secure monitor without any RS-485 series communication port and digital IP camera. Besides, the intellectual surveillance system can control the actions of monitoring and reacting such situations automatically by using the monitoring method.