The invention provides a DVR monitoring system supporting single-channel dual-stream video recording and a method thereof. A video and audio acquisition channel acquires video and audio data, and the video and audio acquisition channel comprises analog video cameras or IPCs; a DSP encoder encodes analog signal input of the video and audio data acquired by the same path of analog video cameras into mainstream data with higher resolution and sub-stream data with lower resolution, or repackages the mainstream and sub-stream data acquired by the same path of IPCs into the mainstream data with higher resolution and the sub-stream data with lower resolution; the mainstream data with higher resolution are cached in a mainstream video recording buffer area, and the sub-stream data with lower resolution are cached in a sub-stream video recording buffer area; and a mainstream and sub-stream video recording scheduling module schedules the mainstream data with higher resolution and the sub-stream data with lower resolution to be stored to video recording storage equipment. Hard disk data storage overhead can be reduced so that network bandwidth can be effectively reduced, and overhead of a client-terminal decoder and the equipment performance requirement can be reduced.