Bangli is one of the districts in Bali that is also experiencing land conversion. The cause of this land conversion is due to the increasing need for development land, due to the increase in population. This will have an impact on reducing food production, socio economic aspects, socio cultural aspects and environmental aspects. Rapid population growth which is also accompanied by an increasing need for housing means that agricultural land is decreasing. Agricultural land is increasingly narrow due to land conversi on for housing and industrial land. This research examines the function and role as well as strategies of Subak in preventing land conversion in Apuan Village. This research is empirical legal research. The research results show that Sub ak has a function and role as a traditional institution which is expected to prevent land conversion with all forms of legal regulations owned by this organization and through intensive appeals and approaches. The life of the Subak community which is based on Tri Hita Karana is expected to be able to increase awareness and determination of Subak manners not to convert their land which will impact on the creation of environmental sustainability and the sustainability of Subak itself.