In this paper, exergy analysis was implemented to improve the intercity bus air-conditioning (AC) system design. Firstly, an inter-city bus with a passenger capacity of 56 people was selected and then its hourly cooling load capacity was determined with the help of cooling load hourly analysis program (HAP). Analyses were performed for different air mixing ratios (MRs) and seasons. Coefficient of performance (COP), exergy efficiency (psi) and exergy destructions (Exdest) of whole system and its each sub-units were evaluated. Results demonstrated that the atmospheric air temperature and air MR substantially affect the inter-city bus AC systems' performance. According to the results obtained for July, when air MR is 0.5, maximum exergy destruction value was calculated as 6.96 kW at compressor. Exergy destruction values were computed as 2.78, 2.61 and 0.99 kW for evaporator, condenser and expansion valve, respectively.