The Shuilu fahui Dharma Ritual (also known as “Waterland Dharma Function”, “Liberation Rite of Water and Land”, and “shuilu fahui”), one of the grandest dharma assemblies in Chinese Buddhism, is characterized by being on a large scale, lasting a long period of time, and having a myriad of excellent merits. The spirit of Shuilu fahui Dharma Ritual is to “practice unobstructed offering with an impartial mind.” However, impartiality and non-obstruction cannot be attained without resorting to one’s cultivation, which is usually neglected in traditional water and land liturgies, or is expected to be actualized by the dharma host and manager of affairs (yue-zhong dharma master). Meanwhile, it is forgotten that the dharma function is meant to offer an opportunity for all participants to practice together. Consequently, the function is reduced to a formality. In fact, the core of the whole water and land liturgy is the practice of the perfect sudden meditation (hereafter perfect meditation). The current version of “Water and Land Liturgy” (Shuilu Yigui) is a collection of the best repentance rituals based on the theory and implementation of teaching and observation of Tiantai School. This study explores the perfect meditation of Tiantai School contained in Water and Land Liturgy from the organization and content of the liturgy, and the arrangement and implementation of the rituals by researching into the “Combined Liturgies of Abstinence Practice of the Universal Deliverance and Grand Feast Assembly for All Sages and Sentient Beings Gathering from the Water and Land Dharma Realms (Fajie Shengfan Shuilu Shenghui Xiuzhai Yigui Huiben)” edited by Master Fayu in 1920’s, while referring to the text of “Fajie Shengfan Shuilu Shenghui Xiuzhai Yigui” written by Master Zhipan in Song Dynasty and revised by Master Lianchi in Ming Dynasty. We know from the Water and Land Liturgy that the abstinence practice in the Shuilu fahui Dharma Ritual is to allow participants to practice perfect meditation with the words in the liturgy through various rituals, in order to capture the spirit of great compassion and impartiality – the real character of all dhammas. The theoretical foundation of Tiantai’s perfect meditation is that the truth of the dharma-realm is perfect interfusion of the three truths, in order to manifest the truth of non-duality of matter and mind, as well as the fact that all dhammas are marvelous. Therefore, an offering can be made to pervade the ten directions and ten dharma-realms. If we understand the identity of phenomena with their underlying principle, the perfect penetration without obstruction, and that all dhammas are marvelous, we are able to make a superior dharma offering, and rediscover our real self. The whole Water and Land Liturgy is the implementation of perfect meditation, as well as the six perfections in myriad actions of the Mahayana bodhisattva’s path. The purpose of the study is to manifest ancestral teachers’ compassionate wishes in their compilation of water and land liturgies, and to allow participants to understand the Buddha’s intentions in his teachings through the content of the liturgy. The characteristics of Water and Land Liturgy are to “practice unobstructed offering with an impartial mind and make donations to all with great compassion.” To actualize impartiality a