At present, in terms of the conservation of archaeological sites, research is mainly focused on the application of emergency conservation measures and temporary consolidation materials, but there are relatively fewer reports on preventive conservation of archaeological sites. In the excavation and preservation project for the sacrificial pit at Sanxingdui site, a preservation system, consisting of archaeological excavation cabins, an environmental control system, an air-quality monitoring system, preventive conservation measures and an intelligent information-monitoring management platform, etc., was established. Before the excavation, through the earthen site-monitoring system and regional meteorological station, information of cultural relic burial environment and regional meteorology was obtained, to provide reference for setting interior environment of the cabins. During the excavation, various preventive conservation measures, such as temperature and humidity control, air sterilization and purification, limitation of the number of people in a cabin and fresh air ventilation, were taken to control the temperature and humidity in the cabin, reduce the amount of bacteria and fungi, lower the concentration of CO₂, and slow the dehydration process of relics (e.g., ivory objects), which effectively controlled the cracking, crisp powdering and mildewing of unearthed cultural relics, hence providing sufficient time for on-site excavations. The innovative exploration and practice of preventive conservation of the sacrificial pit at Sanxingdui site could guide the direction and set an example for the on-site conservation of important archaeological sites in the future.