This paper provides unificaton-based GPSG and LFG analyses of Mandarin questions. First, we briefly introduce four kinds of Mandarin questions, namely, WH-questions, A-not-A questions, disjunctive questions, and particle questions. Their different interrogative messages are adequately encoded with different feature-value pairs. Then, the compatibility of this interrogative information in a simple sentence is investigated. Both the GPSG and LFG approaches provide a straightforward account for their mutual exclusiveness. Finally, the scope of percolation of Mandarin interrogative information is examined. It is suggested that the matrix verb of a complex sentence is responsible for the scope of interrogative information in its complement sentence. According to our observations, Mandarin verbs should be divided into at least three classes. We provide preliminary analyses of this topic. The GPSG analysis relies on the Foot Feature Principle (FFP) and the LFG analysis relies on functional uncertainty. It is shown that the transmitting of Mandarin interrogative information can be adequately accounted for in both GPSG and LFG.