Prefabricated building, as a convenient and burgeoning building form, is worth popularizing. The research is aimed at comprehensively evaluating and analyzing the indoor thermal environment, air quality, and energy consumption of prefabricated buildings. Therefore, indoor temperature distribution, airflow distribution, and energy system of prefabricated buildings are considered. Different building envelopes proposed accord with average temperature standard (18°C) of indoor thermal environment in different climate regions based on simulation results of DeST software. Take the hot-summer and cold-winter region as an example, the distribution of the indoor temperature, air velocity, and the emission characteristics of indoor polluted particles are explored via ANSYS Fluent software. And the energy supply system for the prefabricated auxiliary building, as well as system operation performances and cost components, is studied. Results show the average indoor temperature on typical days in winter (4.1°C) and summer (31.1°C); air-source heat pump needs to activate for the needs of human thermal comfort. Moreover, the indoor air quality can meet the cleanliness standard after polluted particles release 40 s. And the annual cost of system 1 (photovoltaic system, air-source heat pump, and the state grid) is 839.53 $, 269.83 $ lower than system 2 (photovoltaic system, electrical storage, air-source heat pump, and the state grid), whereas the increase of electricity price can significantly reduce the payback period and thus improve the economy of system 2. These findings provide suggestions in terms of indoor thermal environment, cleanliness, and suitable energy supply system to evaluate and facilitate the widespread application of buildings.