A monitoring system including N cameras, a digital video recorder (DVR), a monitor, a remote controller, a receiver and a host is provided. N is a positive integer. The N cameras successively shoot N sceneries, and output N successive images accordingly. The DVR receives and stores the N successive images. The monitor displays a monitoring screen. The remote controller outputs a wireless remote signal. The receiver receives the wireless remote signal and outputs a wire transmit signal accordingly. The host controls the monitor to display at least the successive image in the monitoring screen. The host has an on screen display (OSD) program. When the controller receives the wire transmit signal, the host utilizes the OSD program to process the wire transmit signal to become a screen adjusting signal. The host adjusts the monitoring screen according to the screen adjusting signal.