Method for assisting video compression by using touch screen and monitoring system

A method for assisting video compression by using a touch screen and a monitoring system are provided. The monitoring system comprises a touch screen and at least one image capturing apparatus. Each image capturing apparatus captures a reference frame. A touch operation performed on the touch screen is detected and a motion vector thereof is computed. The image capturing apparatus is moved according to the motion vector to capture a current frame. The reference frame is divided into reference blocks, and a current block in the current frame corresponding to each reference block is searched according to the motion vector. A difference between each reference block and corresponding current block is compared to determine whether to use the motion vector of the touch operation as the motion vector between the reference block and the current block, so as to compress frame data of the reference block and the current block.