Intonation is one of the most important factors of speech expressivity. This paper presents a conversion method for the F0 contours. The F0 segments are represented with discrete cosine transform (DCT) coefficients at the syllable level. Multi-level dynamic features are added to model the temporal correlation between syllables and to constrain the F0 contour at the phrase level. Gaussian mixture models (GMM) are used to map the prosodic features between neutral and expressive speech, and the converted F0 contour is generated under the dynamic features constraints. Experimental evaluation using a database of acted emotional speech shows the effectiveness of the proposed F0 model and conversion method.