Because of the flat terrain and lack of mountains, the annual evaporation of Penghu is greater than the rainfall, and the lack of water resources, the trees are not easy to grow, so it is very precious to become a century old tree, and it also attracts our investigation. And Penghu Tongliang ancient banyan is a well-known old tree scenic spot, so we hope to combine it with sightseeing, in addition to investigating the situation of the old trees, we also hope to I hope to find the trees that will become tourist attractions.In order to complete this research and research objectives, we first collected enough data to make a questionnaire and a tool to measure the height of trees. Then we conducted a series of surveys on old trees. The survey contents were very many, such as: tree height, tree bust, root opening range, etc. then we sorted out the data and exported the results. When looking at the research results, we found that Penghu In fact, all the old trees of are well preserved, but some of them are in very poor condition, even reaching the cut-off situation. Therefore, under our inquiry, the Bureau of agriculture and Fisheries also updated the data of the precious old trees of Penghu at that time. Finally, through the data analysis during our investigation, we found the old trees of Baoding palace, Gangzi village, Baisha Township, which had the opportunity to become the next tourist attraction This study puts forward follow-up suggestions.