The plateau area is characterized by cold and dry conditions, large diurnal temperature variations and strong sunlight. To study the variations in environmental parameters in highland museums, a ten-month monitoring of the temperature, humidity, CO₂ concentration, VOC concentration, light intensity, and ultraviolet intensity was conducted both inside and outside a scripture cabinet of a museum in Lhasa. We accomplished this by analyzing the patterns, characteristics and influencing factors of environmental parameter changes accordingly. The results show that the temperature and humidity inside the cabinet changed seasonally with the external conditions but exhibited smaller diurnal fluctuations, with average daily variations of 0.73℃ and 0.83 percentage points, respectively, compared with 1.6℃ and 4.25 percentage points externally. The scripture cabinet could effectively protect the ancient manuscripts from daily fluctuations in external temperature and humidity. There was no significant correlation between the diurnal variations in temperature and humidity and seasons, indicating good thermal insulation properties of the museum’s structural enclosure. There was a significant positive correlation between the diurnal variations in temperature and the CO₂ concentration, suggesting that a higher number of staff in the storage area led to a greater temperature variation. The VOC in the cabinet was easy to enrich, featuring a higher concentration, and it is recommended to place adsorbent materials such as activated carbon. The light intensity and ultraviolet intensity were extremely low. The current cabinet was generally beneficial to scripture preservation.VOCs tended to accumulate at higher concentrations inside the cabinets, suggesting remedies such as the use of adsorbent materials like activated carbon or replacing the scripture cabinets. The intensities of both light and ultraviolet radiation were extremely low.