Abstract: Child-directed speech objectives are a) attract and hold baby’s attention, b) help process of breaking down language into understandable chunks , c)make the conversation more predictable by keeping the conversation. This paper compares the structures and prosodic feature used during shared reading by two Iranian mothers of two different aged children, i.e. 2.5 and 4. This study carried out through mothers’ speech recording while describing picture book to r children. The compared data from transcription of sessions revealed that the amount of one-word or tow-word utterances and imperative and declarative ones along with prosodic feature (intonation) ,used by mothers ,depends on child semantic knowledge and age. Here declarative utterances were used the most and imperatives the least. The reasons to use different intonation referred to their age to draw their attention.