At present, there exist quite a few troubles in the definition and identification of Tianhuang, such as excessive generalization and misuse of the name of Tianhuang, variance of the measurement criteria for identification of Tianhuang. This paper presents several important problems which deserve full attention in the correct identification of Tianhuang, emphasizes the importance of Tianhuang's secondary characteristics for its identification, and expounds the key points in distinguishing real crust from fake crust.