In this paper, a new statistics-based pitch model for Mandarin speech is proposed. The model considers three major affecting factors on the syllable pitch contour, including lexical tone, prosodic state and inter-syllable coarticulation effect. The study emphasizes on the modeling of inter-syllable coarticulation effect. Interactive affections of neighboring tones and different inter-syllable coarticulation states are considered. Experimental results show that the model performed well even for connected pitch contours of several syllables. Automatic labeling of linguistically meaningful coarticulation states is an extra benefit. So it is a promising F0 model.