Abstract: Beginning with air volume determination in the design of precision air conditioning unit, it presents a detailed comparative analysis of the related requirements for the GB/T19413-2003 and the parameters of the mainstream foreign precision air conditioning unit. The analysis shows that the national standard specifies that the air supply temperature difference must be less than 7℃, and under the condition of sensible heat ratio air volume needed for per kW cooling capacity is at least 376 m^3/h while the air supply temperature difference for most foreign brands is less than 11℃, and under the condition of the same sensible heat ratio, air volume needed for per kW cooling capacity is only 264 m³/h, with air volume reduced by 29.8%, the air outlet temperature being between 13 ℃ and 15 ℃,  and the average noise value of the product reduced by 1.2 dBA. At the same time, the analysis of the temperature control precision and ventilation rate also indicates that the air volume of 264 m³/h can satisfy the requirements. The design of air volume should meet the minimum requirements and increase properly according to the actual situation.

Key words: precision air conditioning; sensible heat ratio; circulation air volume; air supply temperature difference