This paper explores the transformation of ritual from ancient Vedic India to Buddhist China in the Tang Dynasty to see how the alteration of agnihotra as a ritual relates to the development of Buddhist thought and practice. In India, agnihotra is related to the sum rather than sacrifice to fire in origin, as it is the maintenance of fire for the rising sun. Thus, it is appropriate to say that fire is inside the sun s heat and light is emitted from the sun. As a kind of sun-charm, agnihotra is meant to help maintain not only the routine rising of the sun, but also its daily course-from east to west during the day and from west to east during the night. The meaning of agnihhotra was transformed to mean the sacrifice to Agni as well as sacred fire itself in due course of time. In Epic literature, the term is often connected with the maintenance of the sacred fire and offering oblation to it. Ultimately, agnihotra was identified with the general fire sacrifice, and became a means to attain the different worldly goals in human life. In Tantric Buddhism, agnihotra becomes homa and is further divided into worldly and otherworldly in the Mahavairocanasutra. As Buddhist Tantra is inseparable from Mahayanist world of thought, the decipherment of the Tantra ultimately rests on Mahayanist ideals of enlightenment. Thus, while worldly homa is concerned with worldly pursuit and empowerment, otherworldly homa becomes the liht of wisdom of bodhicitta to consume avidya. Homa must have been an important daily ritual in the Tantric temples in the later Tang Dynasty, as we still can witness in Japanese esoteric Buddhism nowadays. Huei-lin compares homa with imperial sacrifice which probably shows the importance of homa in the Tang in terms of its political overtones.