Three-in-one Feng Shui is the theoretical knowledge of three-in-one Feng Shui. Trinity refers to the trinity of life, prosperity and tomb of Jin Mu Fire and Water Fourth Bureau, that is, the trinity of earthly support. If the wood is born in the sea, it is more abundant than the hair, and the tomb is not there. Three-in-one geomantic omen pays attention to parents' three hexagrams, and requires the integration of faucet, sitting degree and nozzle. For example, if the water mouth is four local water mouths and the head and tail are golden dragons, it is required that the cave sitting degree must be controlled within the golden dragon sitting degree. Under each branch of the compass, there are four attributes of Jin Mu's fire and water, such as sub-characters, some of which belong to the golden dragon and some belong to the dragon, so a word has different methods of regulating qi, and different dragon bureaus have different Twelve Shougong, which is not what some scholars think, so the sub-character must be the Water Bureau.

The Trinity School founded by Yang Gong is the mainstream of geomantic omen, and countless friends use the Trinity Theory to explore the Yin-Yang school. Three-in-one geomantic omen also has different branches, including three-in-one ancient method, three-in-one new method and three-in-one upper method. The three-in-one ancient method is the most popular geomantic omen in Ganzhou at present. Its founder is Yang Junsong, the originator of geomantic omen, who advocates using the Twelve Immortals Pantian Shuangshan to remove Shana water. Representative works include Tianyu Jing, Yuchi Jing, Qingnan Gao Yu and so on. It is known as the nine scenic spots of the world. The founder of the Trigonometry is Lai Buyi, a disciple of Yang Gong and a master of the Song Dynasty. He added a human disk to the compass, which integrated the talents of heaven, earth and man. Its plum still uses the three-in-one ancient method to collect water, but now it advocates using 28 families and five elements to cooperate with people to remove sand. Representative works include "Urging Officials" and so on. The three-in-one upward movement was initiated by the declining Confucian scholars Wang and Zhao Jiuzhen in the Ming and Qing Dynasties. The five elements of feng shui, namely dragon, cave, sand, water and direction, are regarded as the final unity, from top to bottom, but the most dangerous dragon and water are relegated to a secondary position. His representative works mainly include Five Strategies of Geography and The Truth of Geography.