This study examines the effectiveness of visual displays in improving the mastery of the forms and functions of English intonation among Chinese L2 students. Over a four-week period, two groups of learners (visual-training and auditory-training) took part in five sessions of intonation training, while a control group received no training. Each session began with a 25-minute lesson on the forms and functions of intonation, followed by a 40-minute practice session. All sentences were presented in communicative contexts. With the aid of speech visualization technology, the visual-training group was taught linguistic categories and English intonation structures, and was encouraged to imitate and practice intonation patterns using visual displays of the intonation of each sentence. The auditory-training group learned and practiced intonation by carefully listening to audio clips of each sentence. Intonation production was assessed using speech data from pre- and post-tests. Results showed that the visual-training group outperformed the other two groups, making the greatest progress in mastering the forms of English intonation (pitch accents and boundary tones) and its functions (expressing prominence and marking modality).