Video surveillance system has a huge market as the number of installed camera shows, especially for the low power ones. This paper proposes a low power quadtree video encoder for video surveillance systems. It features a low complexity motion estimation algorithm, an application specific ME-MC processor, a dedicated qudatree encoder engine and a prediction-based clock gating technique. A chip capable of encoding 30 fps VGA (640×480) at 80MHz was fabricated using 0.18μm CMOS technology. A total of 153K gates with 558Kbits SRAM have been integrated into a 5.0 mm × 3.5 mm die. The power consumption is 40.87mW at 80MHz for VGA 30fps and 1.97mW at 3.3MHz for QCIF 15fps, respectively.