The adverb “Jianzhi” is used frequently in modern Chinese, but most of its previous research focused on “subjectiveness”. To break through this limitation, this paper focused on the syntactic features and main semantic functions of the adverb “Jianzhi”. Firstly, in syntactic features, by organizing the structure with high frequency of “Jianzhi”, it is found that the common feature presented in the verb structure is to pay attention to the characteristics of the nature of the things, and in the adjective structure is to show that mainly modifies the high degree of complements. Secondly, we found that “Jianzhi” has two main semantic functions. The first one is “non-true value marking function” and the other one is “boundary function”. The former means the speaker reminds the listener that the central meaning in the “Jianzhi” sentence is not true, and the latter means when “Jianzhi” is modifying the degree component, it will set a boundary for the component, indicating the degree limit. The commonality of these two semantic functions is [+ default], so the main semantics of “Jianzhi” can be summarized as a temporary default to reach a certain amount or form a certain result, situation.