Abstract: It is intended to air-condition the internal space of the Assembly Hall at Mandalay Technological University (MTU). The main objective of air conditioning is for human comfort and the preservation of equipment. The unit thus consists of refrigeration system, the control system, electrical protection system, air circulation system and ventilation (fresh air damper) exhaust system. The most important function to install an air-conditioning system is to calculate the cooling load and duct design of the Assembly Hall at MTU. But this paper analyses duct design for required air distribution of designed space. After a series of calculation and designing the outcome was a possible solution for an optimum ducting system for our hall. The proposed design is compatible only for Assembly Hall at MTU, but the same design procedures are applicable to large ducting systems in skyscrapers and factories.