The calculation of heat and humidity load serves as the cornerstone of Heating, Ventilation, and Air Conditioning (HVAC) design. Nevertheless, as the heat and humidity load characteristics of underground structures differ substantially from those of above-ground structures, it is a challenge to derive their accurate calculation procedure through engineering experience. Therefore, it is particularly important to carry out quantitative research on heat and humidity load. This study used Design Builder software to study the influence of the design state point of air conditioning in underground buildings on energy consumption. The study showed that compared with the single design temperature of 18°C, setting the temperature of 16°C in winter and 22°C in summer could reduce energy consumption by about 59%. And the hourly heat load, cooling load and humidity load in one year are simulated and calculated so as to quantitatively analyze the characteristics of the load. This provides a database for selecting suitable HVAC equipment. It is further emphasized that dehumidification is the key to HVAC design of underground structures, which provides a reference for similar engineering designs.