Abstract: This article investigates the occurrence of le in imperatives and attempts to outline the syntactical hierarchy of le.Previous research indicates that le in Chinese (the verbal -le and the sentential le) can be construed as the phasal complement (-le₀), the perfective marker (-le₁) and the sentence final aspect particle (le₂).However, in this study it is found that the sentential le in imperatives behaves different from the sentence final aspect particle (le₂) in that it does not express temporal relations of inchoativity or perfectness.On the other hand, it behaves the way the typical sentence final particle does in that it can be deleted, but it cannot be embedded, or co-occur with other sentence final particles or expresses the speaker's attitude of emphasis.Conclusively, le in Chinese consists of a four-layered hierarchy: SaP(le₃)le₂)<(TP)le₁)<(vP)le₀), where -le₁ and le₂ are not allowed in imperatives as the temporal relations they define run against that of imperatives.-Le₀ and le₃ can co-occur in imperatives but are phonetically reduced and realized as one le by the operation of haplology.