While data centers consume a lot of energy, the consumption of water resources cannot be ignored. Air-side economizer, an effective energy-saving technology for data centers, is constrained by outdoor air pollutants. Based on the actual energy consumption, water consumption and air conditioning test data of a data center, taking into account the indoor environmental requirements and the outdoor air pollutant conditions of the data center, the feasibility of applying the air-side economizer was discussed and its calculation method of energy and water consumption was analyzed, and the calculation results were compared with the actual application of the water-side economizer. The results show: The data center has a Power Usage Effectiveness (PUE) of 1.56 and a Mechanical Load Component (MLC) of 0.43 under mechanical cooling and significant energy savings under full free cooling in the water-side economizer, with a PUE of 1.40 and MLC of 0.25. Compared with the period of applying water-side economizer, the PUE of applying air-side economizer is 1.27, MLC is 0.13, the average daily water consumption is about 30% of the cooling tower water consumption, and the Water Use Efficiency (WUE) is 1.01, so the energy and water saving potential is much higher than that of water-side economizer. In addition, the water-saving performance of the air-side economizer will be further improved as the specification requirements for the lower limit of humidity in the data room environment are reduced. This provides a basis for subsequent research on the combination of air-side and water-side economizers , as well as for proposing the idea of " air-side prioritization, water-side supplementation".