Environmental protection is one of the eight important missions of Tzu Chi Foundation. Over the past 30 years, it has attracted a large group of environmental protection volunteers from both at home and abroad. In her teachings and special books, Master Cheng Yen has a lot of sincere reminders about environmental protection. This research explores how the important contemporary religious, Master Cheng Yen, teaches Tzu Chi people to practice environmental protection in order to achieve care for the society and the advocacy of Buddhism, and to understand the meaning of "purity at the source". Master Cheng Yen's humanistic Buddhism lies in the practice of Buddhism and the creation of a pure land on earth. She put forward the idea of maintaining minimum material satisfaction to counteract the waste of luxury, and put forward that vegetarianism is the environmental protection of the soul as well as the source of the environmental protection of the earth. Master Cheng Yan instructed Tzu Chi volunteers to devote themselves to environmental protection, so as to create a world like the Pure Land. Emphasize that the pure land situation is born from the heart, therefore, the source of purity should start from the purification of the human heart. In summary, to create a pure land on earth by purifying people's hearts is exactly the practice and goal of Master Cheng Yen on humanistic Buddhism.