The appraisal system, which was founded by Martin, White and other scholars in the 1990s, completed the interpersonal function of Systemic Functional Linguistics. It includes three major sub-systems, namely the engagement system, attitude system and graduation system. At present, the appraisal system is widely used in the study of various texts. As a business card of foreign exchanges, national image plays an important role in enhancing national competitiveness and promoting international cooperation and development. As a special type of film and television, a documentary takes real life as the material, people and real events as the objects and tries to convey the most authentic information to the audience. The documentary series, A Bite of China toke the Chinese diet culture as the core and left a deep impression on the Chinese audience through the relaxed and lively narrative rhythm. What's more, its English version, translated by BBC, shows the daily diet of Chinese to an overseas audience. In this way, Chinese culture got dissemination, and also it shaped the Chinese national image. At present, most of the studies on documentaries are derived from the perspective of translation and communication science, while from the perspective of appraisal systems to study documentaries are few. Therefore, the author intends to study the construction of the Chinese national image of the English version of A Bite of China (I) from the perspective of the appraisal system.