This paper first reviews the theories of the former, then introduces a new concept of Cultural Corridor which is suitable for China, and explains its core idea. At the base of the path's culture, Cultural Corridor has special linear cultural heritage based on its natural and cultural settings, and reflects multi-dimensional, continuous and reciprocal exchanges of goods, ideas, knowledge and values between peoples and regions over significant periods of time due to people's migration and communication. Identifying the extent is an important basic work, which can help deepen its related study. This paper aims to provide a sound method to identify the corridor's extent. Firstly, the cultural elements related to Cultural Corridor are recognized through experts' comments. Then, a formula is deduced to calculate the "affective force radius" of every element with the comments of experts. Based on the radius, the buffer zone of every element is made with the software of GIS, and then the extent of Cultural Corridor is obtained. Finally, this paper provides an index system to analyze, construct and optimize tourism spatial structure from three aspects: junction, path and domain. According to the above results, the domain of Cultural Corridor can be obtained easily.