This work aims to model and simulate an absorption cooling system using solar flat- plate receiver with water lithium bromide (li.Br-H2O) mixture as a working fluid, and to select the optimum type for absorption cooling system, which have suitable application in Iraq. Weather conditions for Erbil city have been selected. Coefficient of performance (COP) for a single, double (series and parallel), half and triple effect of an absorption cooling system are calculated and optimized. COP Prediction, hot water temperature, and the rate of heat transfer have been simulated and represented by using TRNSYS and EES programs. Active area of the solar flat-plate receiver is calculated and optimized for five suggested areas of (140, 150, 160, 170, and 180 m 2). Average heating load, average daily - radiation and cooling load for summer months (June, July, August, and September) have been calculated. The results indicated that, the superior type of the four absorption-cooling systems is a single effect, which has COP 80% at generator temperature of (81 °C). Also the results indicated that the optimum area of solar flat-plate receiver was 160 m2 which has achieved the maximum capacity of cooling power and consumed capacity in the generator (50, and 62.5) kW respectively. I think, according to the previous studies , the current work is the first in Iraq because it approved that, single effect type is an efficient and more relevant type for good working under Iraqi climate by using solar flat–plate receiver and suitable to apply it experimentally in a wide range.