MAC Unit is the basic building block of any signal processing hardware. At present, every field, such as medicine, astronomy, geography, industry, embedded system, etc requires applications of digital image processing. These fields require real-time processing, and efficiency is necessary in the implementation of digital image processing. Multiplier -and Accumulator (MAC) Units perform the mathematical operation such as convolution. They are the fundamental digital block and are the most computationally and resource-demanding unit. A MAC unit with optimum performance and power consumption is always desired. The primary contribution of this paper is investigating the existing work and techniques used by several authors to minimize the power consumption in the design of MAC Unit. This review can provide aninsight to the beginners in the VLSI Arithmetic Circuit Design to gain more idea on Low power MAC Unit Design.