In the urbanization process, phenomena such as the urban heat island effect exacerbate climatic deteriorations, leading to environmental issues in cities. Campus areas, as significant ecological components within the urban environment, play a crucial role in environmental regulation. This paper investigates the impact of outdoor physical environments in campuses on users’ thermal comfort from the perspective of thermal comfort. Using surveys, meteorological measurements, and behavioral analysis, this study examines four distinctive spaces within a campus in Xi’an, establishing a thermal comfort baseline for the population in Xi’an’s campus spaces. The research results indicate: (1) Globe temperature (Tg), air velocity (Va), air temperature (Ta), and ground temperature (G) are the primary factors affecting students’ thermal sensations in campus open spaces. Respondents tended to improve their thermal sensations through changes in humidity and solar radiation. (2) In the campus open spaces of Xi’an, the overall NPET of the subjects was 13.9 °C, with the NPETR ranging from 9.4 to 18.4 °C. (3) The preferred warmth temperature for university students in Xi’an is 15.15 °C, which is 1.25 °C higher than the NPET (13.9 °C).