This study examined the use of intonation in children with single word sentences and investigated the communicative functions of pitch range and pitch direction. Two children aged 13months were observed in interaction with their mothers for 10 months. The vocalizations were coded separately for communicative function and for prosodic feature. Results show that level tones are used most frequently, and pitch range is higher for request than declaration or answer and lower for answer than request or declaration. And trends in prosodic contours were observed in request, declaration, and answer respectively. For one child, rising tones were frequently associated with request whereas rising-falling tone with declaration. For the other child, rising-level tones were more frequently associated with request whereas falling-level appeared more often in conjunction with declaration. These trends appeared more distinct in proportion as they grow in months. This result indicate that the way to express communicative functions transfer gradually from differentiating pitch range to diversify pitch direction.