Alternating current (AC) is the main driving force in the industries and residential areas, but for the long transmission line (more than 400 miles) AC transmission is more expensive than that of direct current (DC). Technically, AC transmission line control is more complicated because of the frequency. DC transmission does not have these limitations, which has led to build long HVDC transmission lines over the last 40 years. HVDC technology made possible to transfer bulk power over long distances. This paper presents a comparative evaluation of HVDC and HVAC transmission systems..This article will clarify the HVDC and HVAC SYSTEMS .